JPH09149377A - Video server device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set a data receiving time at a terminal equal to or below a time slot period time by providing a completion look-ahead instructing part which gives a lock-ahead instruction to a video server device when there is a free slot in a buffer part at the time of end of data reading. SOLUTION: Plural terminals 14 providing a computer, etc., are connected to a transmission part 13 via a network, etc. When the terminals 14 request data, buffer parts 12 store data read from a storage device 11. The lock-ahead instruction part 15 instructs the storage device 11 to look-ahead at each time slot period when there is the free slot in the buffer parts 12. When data reading to the buffer parts 12 is completed as a succeeding data look-ahead instruction part, the completion look-ahead instruction part 16 gives the look-ahead instruction to the storage device 11 at the head of the time slot period when there is the free slot in the buffer parts 12. Then, a program serching time is shortened so that the time for receiving data by the terminals is shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video server device for servicing data such as moving image data and character information in response to requests from a plurality of terminals.

[0002]

2. Description of the Related Art In recent years, due to the development of computer technology,
Video server devices that provide data such as moving image data and character information in response to requests from a plurality of terminals have come into use. Japanese Patent Application Laid-Open No. 4-26908
No. 7, there is disclosed a multiple reading method of a video server device that simultaneously serves moving image data to a plurality of terminals. However, since the above-mentioned document does not show a method for efficiently reading the storage device, it is not possible to service the moving picture data at the same time as several tens of terminals.

Therefore, Proc. 1st ACM I
international Conference on
"Streaming RAID-A Dis" described in Multimedia August 1993.
k Array Management System
For Video Files ”paper and Nikkei New Media supplementary book“ Interactive TV ”(19
In the method introduced in (October 1994), in order to efficiently read the data from the disk device in which the moving image data is stored, the movement of the disk head of the disk device with respect to a plurality of read commands in each time slot period. A method of reading data by using an elevator seek method for increasing the performance and increasing the number of terminals is shown, in which sorting is performed so as to minimize.

[0004]

However, in the above-mentioned "Streaming RAID" paper and "Interactive TV" magazine, a method for multiple reading moving image data and a method for reading a disk at high speed are described. There is a problem in that it is necessary to wait for a time slot period or more after requesting the moving image data until the requested moving image data is sent from the video server device to the terminal.

In consideration of such problems of the conventional video server device, the present invention makes the time from the terminal requesting the moving image data until receiving the requested data from the video server device less than the time slot cycle time. It is an object of the present invention to provide a video server device capable of achieving the following.

[0006]

According to the present invention, there is provided a storage device for storing data, a pre-reading instruction section for outputting a data read instruction to the storage device for each time slot period based on a data request from a terminal, and a data reading device. If there is an empty slot in the time slot period when the first data read instruction is output from the prefetch instruction unit in response to the request, the empty slot is used to issue a data read instruction for reading at least the next data. A next data prefetching instruction unit for outputting to the storage device, a buffer unit for temporarily storing the data read from the storage device by the data reading instruction, and a sending unit for sending the data stored in the buffer unit to the terminal , The sending part is a terminal that sends out the first data requested by the terminal as soon as it is stored in the buffer part. It is a Osaba apparatus.

As a result, the data read start speed can be increased by starting the data read from the storage device not only every time slot cycle but also during the time slot cycle. The start-up time of the terminal connected to the device can be shortened.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing an embodiment.

FIG. 1 is a block diagram showing a video server device according to an embodiment of the present invention. In FIG. 1, the storage device 11 is configured by a SCSI disk device or the like that stores moving image data and the like. Buffer unit 12-1 to n
Is a DR that accumulates the data read from the storage device 11.
It is composed of AM or the like, and n pieces are provided in FIG. The sending unit 13 sends each data stored in the buffer units 12-1 to 12-n to a network or the like. Terminals 14-1 to n
Is connected to the sending unit 13 via a network or the like,
It is composed of a personal computer or the like that reproduces the transmitted moving image data. If there is a vacancy in the buffer units 12-1 to 12-n, the prefetch instruction unit 15 issues a prefetch instruction to the storage device 11 for each time slot cycle. The completion read-ahead instruction unit 16 as the next-data read-ahead instruction unit, when the data reading from the storage device 11 to the buffer units 12-1 to 12-n is completed, if there is a vacancy in the buffer units 12-1 to n, the storage device 11 Give prefetch instructions to. Look-ahead restriction unit 17
Divides the prefetch instruction issued from the prefetch instruction section 15 or the complete prefetch instruction section 16 into a plurality of sections.

Next, referring to the drawings of the present embodiment, the terminal 14-1 stores moving image data A stored in the storage device 11, the terminal 14-2 stores moving image data B stored in the storage device 11, Similarly, a case where the terminals 14 to 26 reproduce up to the moving image data Z stored in the storage device 11 will be described. FIG. 2 shows the storage device 1 for each time slot period.
4 is a timing chart showing how the data of No. 1 is passed to the buffer units 12-1 to 12-n and the sending unit 13. However, since the figure becomes complicated, the timing charts of the terminals 14-3 and thereafter are omitted.

First, a case in which the video server apparatus operates as a normal video server apparatus, that is, a video server apparatus similar to the conventional one will be described. (1) The pre-reading instruction unit 15 issues a pre-reading instruction up to the start block Z1 of the moving image data Z in the order of the start block A1 of the moving image data A and the start block B1 of the moving image data B at the beginning of the time slot cycle. Instruct. (2) The prefetch restriction unit 17 outputs the data read instruction issued from the prefetch instruction unit 15 to the storage device 11 as it is. (3) The storage device 11 changes the command order of the data read instructions output from the prefetch limiting unit 17 (by elevator seek) so that the data can be read from the disk device at high speed, and the buffer units 12-1 to 12-1. Read data to n. With this, the state of the first cycle of FIG. 2 is obtained. (4) When the next time slot period comes, the sending unit 13 starts transmitting to each terminal at the same time as the moving image data A1, B1, ..., Z1, and the terminals 14-1 to 14-n receive the moving image data and display the moving image. To do. (5) Furthermore, the prefetching instruction unit 15 instructs the prefetching limiting unit 17 to read the data of the next block of moving image data. With this, the state of the second cycle of FIG. 2 is obtained. After (6), the above operations (2) to (5) are repeated. The state becomes the state after the third cycle in FIG.

As described above, moving image data is served to a plurality of terminals. In this case, the start time takes more than the time slot period.

Next, a case where the number of terminals that have requested data is 1 will be described with reference to FIGS. 3 and 4.

Since the operation of the video server device is the same as the operations (1) to (6), as shown in FIG.
After the terminal 14-1 requests the reproduction of the moving image data, the data is read into the buffer and transmitted, and the terminal 14-1 actually
It takes more than the time slot period until -1 receives the moving image data.

At this time, since there is a vacancy in the time slot period, the next data can be read out in this section and the data of the first block can be transmitted immediately to shorten the start time. Therefore, when the storage device 11 uses the completion read-ahead instruction unit 16 to process all the data read instructions specified at the beginning of the time slot cycle, the completion read-ahead unit 16 issues a data read instruction to be performed in the next cycle. I will send it to you. By doing so, as shown in FIG. 4, it becomes possible to read the data A1 and A2 in the first cycle of the time slot, and the sending unit 13 sends the data of A1 and the storage device 11 reads the data of A1. It can be done immediately after.

As described above, when the number of terminals is small and the amount of data to be read in the time slot cycle is small, the start time can be set to be less than the time slot cycle.

Next, a case where the number of terminals requesting data is such that a part of the time slot period is used and a part thereof is vacant will be described with reference to FIGS. 5 and 6.

The operation of the video server device is as described in (1) above.
Since the operations from (1) to (6) and the completion prefetching instruction unit 16 described above are used, the timing of reading the moving image data A is as shown in FIG. In the first cycle, B1, C1, and D1 for which a read instruction has already been issued are read from the storage device 11,
Immediately after that, the data of A1 and A2 are read from the completion prefetching unit 16. At this time, the cue time is 4/5 of the time slot cycle, that is, up to the vacant position of the time slot of the first cycle.

Therefore, as shown in FIG. 6, the prefetch limiting unit 17 divides the data read instruction from the prefetch instruction unit 15 and the complete prefetch instruction unit 16 for each data of two terminals. However, if you divide the data read instruction, you will not be able to perform elevator seeks in the divided parts.
Since the number of data that can be prefetched in the time slot period decreases, the division is performed only when the number of terminals is small. FIG. 6 shows the timing when the prefetch limiting unit 17 divides the data read instruction in this way.

In this case, the read-ahead restriction unit 17 divides the data read instruction into B1, C1 and D1, and B1, C1 are divided.
The data read instruction of No. 1 is sent to the storage device 11. Then, after the storage device 11 has read B1 and C1, the transmission unit 13 instructs the storage device 11 to read the data A1 and A2, so that the transmission unit 13 transmits the data A1 for a time period of 3/5 of the time slot period. You can do it with.

As described above, when the number of terminals is small and the amount of data to be read in the time slot period is small, the start time can be made shorter than the time slot period.

As described above, according to the present invention, it is possible to advance the data read start time by not only starting the data read from the storage device for each time slot period but also during the middle of the time slot period. Therefore, it is possible to shorten the cue time of the terminal connected to the video server device.

In the above embodiment, the case where there is one time slot has been described, but the present invention is not limited to this, and there may be a plurality of time slots.

Further, in the above embodiment, the complete prefetching instruction section is used as the next data prefetching instruction section, but instead of this, it is possible to read data from the storage device every n division cycles of the time slot cycle. For example, it may be a division prefetch instruction unit that issues a data read instruction to the storage device.

Further, in the above embodiment, the prefetching instruction section, the completion instructing section, the prefetching limiting section and the like are constituted by dedicated hardware, but instead, the same function is realized by software using a computer. You may.

[0026]

As is apparent from the above description, according to the present invention, the time from the terminal requesting the moving image data until receiving the requested data from the video server device can be less than the time slot cycle time. It has advantages.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a video server device according to an embodiment of the present invention.

FIG. 2 is a timing diagram of a time slot period in a normal case.

FIG. 3 is a timing diagram of a time slot cycle when the number of terminals is 1.

FIG. 4 is a timing diagram of a time slot period when the prefetch completion unit is operated with the number of terminals of FIG.

FIG. 5 is a timing chart of a time slot period when the number of terminals is four.

6 is a timing diagram of a time slot period when the prefetch limiting unit is operated with the number of terminals of FIG. 5 described above.

[Explanation of symbols]

 11 storage device 12-1 to n buffer unit 1 to n 13 sending unit 14-1 to n terminal 1 to n 15 prefetch instruction unit 16 completion prefetch instruction unit 17 prefetch restriction unit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G09G 5/00 555 9377-5H G09G 5/00 555D H04N 5/78 H04N 5/78 B

Claims (3)

[Claims] 1. A storage device for storing data, a pre-reading instruction section for outputting a data read instruction to the storage device for each time slot period based on a data request from a terminal, and the pre-reading for the data request. If there is a vacant slot during the time slot period when the first data read instruction is output from the instruction unit, the vacant slot is used to output a data read instruction for reading at least the next data to the storage device. A next data prefetching instruction unit, a buffer unit for temporarily storing the data read from the storage device by the data reading instruction, and a sending unit for sending the data stored in the buffer unit to the terminal, As soon as the first data requested by the terminal is stored in the buffer unit, the sending unit immediately sends the first data. A video server device characterized by transmitting data. 2. The next data prefetching instruction unit continuously outputs a data reading instruction for the next data to the storage device when the first data reading instruction is completed. Video server device. 3. Further, when a data read instruction to another terminal has already been used in some slots of the time slot cycle and there is an empty slot in some of the slots, a data read instruction of the used slot is given. By dividing at least one of the empty slots to the front side of the time slot cycle, and using the moved empty slot to output a data read instruction of the terminal to the storage device. 3. The video server device according to claim 1, further comprising a prefetch limiting unit that limits a data read instruction from the prefetch instruction unit or the next data prefetch instruction unit.