JP3219953B2 - Media server system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to audio and video,
Or accumulate a lot of various media information such as text,
In response to a request from a terminal device, the media server system that transmits the requested media information and enables playback on the terminal device, and in particular, enhances information transmission efficiency,
Media information can be provided to more terminal devices.

[0002]

2. Description of the Related Art In a media server system, time-continuous information such as audio and video or non-time-continuous information such as text is compression-encoded and stored in a disk of a media server. The terminal device requests the required media information. The media server sends the media information to the terminal device in response to each request, and the terminal device decompresses and decodes the received signal and reproduces the media information.

[0003] The multi-terminal connection technique in the media server system is realized by, for example, reading from a disk in a time-division manner as described in Japanese Patent Application Laid-Open No. H4-269087.

As shown in FIG. 5, the conventional media server system includes a disk device 1 for storing and reproducing compression-encoded video information with audio, and a display device for decompressing and decoding received information to display video and audio. A plurality of terminal systems, a switch 2 for distributing reproduction information reproduced by the disk device 1 to each terminal system, and a reproduction operation of the disk device 1 and a switching operation of the switch 3 according to a signal input from each terminal system. Each terminal system includes a buffer memory 41 to 4n for writing compressed and encoded video information reproduced by the disk device 1, and a compression and encoded video information. Decompressors 51-5n for decompressing and decoding
And terminal devices 61 to 6n having monitors 71 to 7n.

[0005] The buffer memories 41 to 4n store two of a and b.
A buffer memory 41a, 41b-4n which is composed of a semiconductor memory having a storage area divided into two.
a and 4nb can operate independently.

On the disk of the disk device 1, a plurality of pieces of information are shredded so that a plurality of pieces of information can be transmitted in a time-division manner, and the pieces are recorded in a state in which the pieces are periodically arranged in the order of information. The original information is reproduced by taking out the pieces of information at regular intervals and joining them together.

The disk device 1 outputs a plurality of pieces of read information using time slots TS1 to TSn, as shown in FIG. The first part of one piece of video information is output as a time slot TS1 in the first cycle, and the subsequent part is output as TS2 in the second cycle, and so on. Similarly, different video information is output using the time slots TS2 to TSn.

The switch 2 stores the reproduction information transmitted in each time slot in buffer memories 41a, 41b to 4na, 4nb.
Sort into one of

[0009] It is assumed that the user inputs number 1 from the operation panel of the terminal device 61 of the first terminal system in order to view the first video information. This number is input to the control device 3 via a control line, and the control device 3 instructs the disk device 1 to perform reproduction, and instructs the switch 2 to
The switching connection is instructed so that only the reproduction information of the time slot TS1 transmitting the first video information is transmitted to the buffer memory 41.

[0010] Upon receiving the command, the disk device 1 starts reproduction, and the reproduced first video information is a time slot TS.
1, the second video information is transmitted to the switch 2 by the time slot TS2, and the # and n-th video information is transmitted to the switch 2 by the time slot TSn. Send to 41.

As shown in FIG. 6, the reproduction information transmitted in the first period TS1 is stored in the buffer memory 41 of the first terminal system.
is written to the buffer memory 41a, and the expanded information is sent to the video monitor 71 for one cycle immediately after the writing to the buffer memory 41a is completed, where the image is displayed and the audio Flows. Then, in the last part where the decompression information is sent from the decompressor 51 to the video monitor 71,
The reproduction information transmitted in the second period TS1 is written into the buffer memory 41b. This information is sent to the video monitor 71 for one period immediately thereafter, where an image is displayed and a sound is played.

The reproduction information output in the time slot TS1 is alternately written into the buffer memories 41a and 41b, whereby the first video information is reproduced on the monitor 71 without any interruption.

At this time, the terminal device 62 of the second terminal system
Similarly, the second video information can be reproduced on the monitor 72 by alternately writing the reproduction information output from the TS2 to the buffer memories 42a and 42b. The terminal device can also reproduce video information from the reproduction information output by each of the time slots.

As described above, in the media server system, although there is only one disk device 1 storing video information, n terminal devices are connected and desired video information is simultaneously transmitted to each terminal. Can be provided.

[0015]

However, in the conventional media server system, when playing back video information, one
Assign one time slot to one terminal,
The same cycle is set for the information reading cycle and the time slot time by this time slot. Therefore, if information with different bit rates is mixed due to differences in the compression rate, etc., in the stored compressed and encoded information, the time slot time is set uniformly to satisfy the highest bit rate There is a need to.

As a result, information which has a high compression ratio and can be read out in a short time and transmitted at a low bit rate is also
The reading and transmission are performed in the same time as the information having a low compression ratio, and the reading efficiency and the transmission efficiency of the entire information are reduced.

Further, even when non-time continuous information such as text is mixed in the compression-encoded information, it is the same as time-continuous information such as audio and video, although it is not necessary to send the information continuously. Since the time slots are allocated and the time slots are continuously transmitted, information transmission efficiency is poor.

The present invention is intended to solve such a conventional problem. The present invention is applicable to a case where time-continuous information and non-time-continuous information are mixed in accumulated information or time-continuous information having different bit rates is mixed. It is an object of the present invention to provide a media server system that improves information reading efficiency and transmission efficiency, thereby enabling information to be provided to a large number of terminals.

[0019]

Therefore, according to the present invention, there is provided a media server which provides compressed and encoded time continuous information and / or non-time continuous information, and information provided from the media server, which is decompressed, decoded and reproduced. In a media server system comprising a terminal that performs
Cycle from the disk device that distributes and stores the information provided to the terminal in block units and the bit rate requested by the terminal
Per block read request number per cycle
Block read request number so that it becomes a positive number.
Assigned to timeslot, using the time slot
A multiple access controller to communicate block read request to the disk device, Di based on the block read request
Blocks of information read from the disk device is provided with a media transmission control means for outputting requests received continuously or discontinuously to the terminal.

[0020] Also, the multiple access control means may be a
When dynamically assigning the number of block read requests to lots
And one terminal based on the bit rate required by each terminal.
Total number of block read requests assigned to
Time slot so that the total does not exceed the reference value N.
The number of block read requests is assigned.
Also, in this time slot, a distinction is made between a synchronous slot and an asynchronous slot, and the multiple access control means uses the synchronous slot to determine a fixed number of block units of information to be read for each terminal for each terminal. convey block read request of the block being in the disk apparatus, using an asynchronous slots, number block read request the block is not determined to be constant for each terminal block
The are configured to communicate to a disk device.

When the number of block read requests assigned to the synchronization slot exceeds the reference value N , the multiple access control means reads the block of the block exceeding the reference value N.
The output request is transmitted to the disk device using another synchronous slot or asynchronous slot within the same cycle.

[0022]

Therefore, when a certain terminal outputs a request to acquire time-continuous information at an arbitrary bit rate, a time slot for transmitting the request of the terminal to the disk device is allocated. Is set in accordance with the bit rate.
Data specifying the number of block units of the time continuous information to be read is sequentially input to the assigned time slot.

The read requests held in the time slots are sequentially transmitted to the disk device.
The requested block is read and sent to the media transmission control means, which transmits the read block to the destination terminal at the bit rate. As described above, in the media server system of the present invention, information is read according to the bit rate and transmitted according to the bit rate, so that information reading efficiency and transmission efficiency are high.

For the non-time continuous information, a read request to the disk device is made using an asynchronous slot or a vacant synchronous slot. As long as the asynchronous slot does not exceed the upper limit (reference value N) of the number of blocks for which a read request can be made, a read request from any terminal can be transmitted to the disk device. When the number of block read requests for non-time continuous information exceeds the upper limit, the excess is transmitted to the disk device using an asynchronous slot or a free synchronous slot in the next cycle.

When the number of block read requests for the time-continuous information exceeds the upper limit, the excess read request is transmitted to the disk device using a vacant synchronous slot or asynchronous slot in the same cycle. Isochronism is ensured.

[0026]

【Example】

(First Embodiment) As shown in FIG. 1, a media server system according to a first embodiment of the present invention includes a media server MS for providing information, and terminals TG1 to TG1 for receiving information.
TGn, the media server MS stores disk devices 11 to 1m in which compression-encoded video information with audio is distributed and stored in units of a block of a certain size, and blocks of video information to be read for each terminal. A multiple access control device (MAC) 30 for transmitting to a disk device using a time slot, a request management unit 36 for receiving a video information acquisition request from each terminal, and a video information to be read based on the request content of each terminal. A request editing unit 35 for inputting the address of a block into each time slot, a media transmission control device (MTC) 22 for outputting media information reproduced by the disk devices 11 to 1m to a destination terminal, and a time slot transmitted. Request to read a block
And a switch 21 for transmitting the media information read by the disk device 11-1m to the MTC 22.
The MAC 30 transmits the request of each terminal unit to the disk device 11 to 1 m
A time slot management unit 32 for allocating time slots Q1 to Qr34 to be transmitted to each terminal unit, and a bit rate control unit 33 for setting the number of blocks to be continuously read from the disk device in time according to the bit rate of accumulated information. And a switch 31 for switching the time slots Q1 to Qr output to the switch 21 at regular time intervals. The time slot management unit 32 also checks whether the number of block read requests actually transmitted using each time slot is not too large.

The terminal units TG1 to TGn include ordinary buffer memories 41 to 4n for temporarily storing received information and decompressors 51 to 5n for decompressing and decoding the stored media information.
And a media output unit 71 for displaying the decompressed and decoded information.
~ 7n.

In this media server system, the terminal unit requests the provision of media information by designating the type of information, its bit rate, and the playback position.

In response, the MAC of the media server MS
30 cooperates with the request editing unit 35 to store the blocks to be read in the time slots Q1 to Q
Requests one after another using r. The disk device 11-1m is M
The requested blocks are sequentially read from the AC 30 and output to the media transmission control device 22.
Sends the compression-encoded block of video information to each terminal at the required bit rate. In each terminal unit, the received video information is decompressed by the decompressor and then displayed on the display unit sequentially.

At this time, it is necessary to deliver the compression-encoded reproduction information to each terminal unit so that the video and audio when the data is expanded and decoded and reproduced are not interrupted. To satisfy this requirement, the bit rate control unit 33 of the MAC 30 controls the video display so that the video display is not interrupted.
The operation for setting the minimum number of blocks that does not fall below the bit rate as the number of read requests is performed, and the time slot management unit 32 controls the time slot for transmitting the request of each terminal unit so that the number of read requests does not concentrate at one time. Is performed. Then, the request editing unit 35 inputs an address designating the number of blocks set by the bit rate control unit 33 of the video information requested by each terminal to a time slot assigned to each terminal unit.

The disk devices 11 to 1m to which the read request has been transmitted by the time slots read only specified blocks of video information. As a result, the disk devices 11 to
From 1m, the number of blocks corresponding to the bit rate is sequentially read.

Now, the operation of this system will be described assuming that the user has requested the provision of media information using, for example, the terminal unit TG1.

The user uses the terminal unit TG1 to input a request for the type of media information to be sought, its bit rate, and the playback position. This request is sent to the media server M
The request is input to the request management unit 36 of S, the request editing unit 35, the time slot management unit 32 of the MAC 30 and the MTC
Sent to 22.

The time slot management unit 32 receiving this request allocates, for example, Q1 as a time slot for transmitting the request of the terminal unit TG1. Similarly, if there is a request from another terminal unit, a time slot for transmitting the request is allocated. In this case, the number of terminals allocated to one time slot is not limited to one.

The allocation of the time slots is performed in order to prevent the timing of the block read requests from each terminal unit from being concentrated at a single point in time and to prevent the number of block read requests from exceeding the read capability of the disk device. Therefore, a reference value N of the number of block read requests transmitted in one time slot is set in consideration of the read capability of the disk device (this N is referred to as "the average value of the number of block read requests in the time slot"). A time slot is allocated to each terminal so that the total value of the number of block read requests obtained from the bit rate requested by each terminal does not exceed N.

The method of assigning time slots will be described in more detail with reference to FIG.

Now, as shown in FIG. 2, the terminal unit TG1,
Time slot Q1 is assigned to TG2 and TG3,
It is assumed that the time slot Q2 is allocated to the terminal units TGu and TGu + 1, and the time slot Qr is allocated to the terminal units TGu-1 and TGu.

The number of blocks per cycle calculated from the bit rate v required by the terminal unit TG1 is 1.5.
If it is determined that the number of blocks is one, it is impossible to request the disk devices 11 to 1m to read from the middle of the block. Therefore, in cycle 1, two blocks are read, and in cycle 2, one block is read. The readout of the blocks is adjusted so that the average number of block readout requests becomes 1.5 by requesting. The number of block read requests for each cycle is determined by the bit rate control unit 33 described later.
Is calculated.

The time slot management section 32 allocates time slots to the terminals so that the total number of average block read requests obtained from the bit rate requested by the allocated terminals does not exceed N. In the example of FIG. 2, the average number of block read requests corresponding to the bit rate requested by the terminal unit TG1 is 3/2, and the average number of block read requests corresponding to the bit rate of the terminal unit TG2 is 4 /.
3, and assuming that the average number of block read requests corresponding to the bit rate of the terminal unit TG3 is 7/3, 3/2
When the sum of + 4/3 + 7/3 does not exceed N, TG1, TG2, and TG3 are allocated to the time slot Q1.

If a new media information acquisition request is issued from the terminal unit TG4, the value obtained by adding the number of average block read requests corresponding to the bit rate required by the terminal unit TG4 to the previous total value exceeds N. In such a case, an empty time slot other than Q1 is allocated to the terminal unit TG4, and if there is no empty time slot, the media acquisition request of the terminal unit TG4 is rejected.
FIG. 3 shows a procedure for allocating time slots by the time slot management unit 32.

The time slot management unit 32 that has assigned the time slot notifies the bit rate control unit 33 of the terminal assigned to the time slot and the bit rate requested by the terminal.

The bit rate control unit 33 receiving this notification
Calculates the number of block requests in each cycle of each terminal unit based on the bit rate requested by each terminal unit. In the case of the terminal unit TG1 in which the average number of block read requests is 1.5, the number of block requests is 2 in cycle 1 and 1 in cycle 2 as described above. The calculated number of block requests for each terminal unit is notified to the request editing unit 35 together with information for notifying the time slot allocated to the terminal unit.

The request editing unit 35 converts the information sent from the bit rate control unit 33 and the media information type and playback position requested by each terminal unit sent from the request management unit 36 into each terminal unit. A request is created which specifies the individual blocks of video information to be transmitted and this request is entered into the time slots assigned to each terminal.

The time slot management section 32 checks whether the number of block read requests actually transmitted by this time slot is not excessive. This is because even if time slots are allocated to each terminal as shown in FIG. 2, the total number of time slots in each cycle is allocated in order to allocate the average number of block read requests of each terminal to an integer in each cycle. This is because the number of block read requests (nqi-j) may become excessive.

In order to manage the number of block read requests per time slot, a value Nmax (this Nmax is called "maximum value of time slot block read requests") corresponding to the maximum value of the read capability of the disk device is set. The time slot management unit 32 determines that nqi-j is Nma
x or less, all the block read requests held in the time slots are transmitted to the disk device, and nqi-
When j exceeds Nmax, of the block read requests held in the time slot, requests for Nmax are transmitted in the time slot, and for requests exceeding Nmax, another free time slot is used. To send.

However, the use of the empty time slot is limited only to the case where the underflow does not occur (the continuity is maintained) even by the transmission using the empty time slot. Also, when there is a request from the terminal unit assigned to the time slot, that request takes precedence and Nma
Requests exceeding x are used only when there is free space. If there is no free time slot satisfying these conditions, requests exceeding Nmax are discarded.

FIG. 4 shows a processing flow when the time slot management section 32 controls the number of block read requests per time slot.

The time slot holding the request recognized by the time slot management section 33 is output to the switch 31, and this request is sent from the switch 31 to the switch 21. When the output of one time slot Q1 is completed, the time slot management unit 32 notifies the bit rate control unit 33 of the terminal assigned to the next time slot Q2 and the bit rate required by the terminal. By this repetition, the time slots Q1 to Qr holding the requests are sequentially output to the switch 31, and these requests are sent to the switch 21 in order.

The switch 21 sequentially sends the received requests to the disk devices 11 to 1m storing the blocks included in the requests. The disk device reads the designated blocks of the media information to be stored in the requested order, and outputs the read information to the media transmission control device MTC22. M
The TC 22 sequentially outputs the read media information to the destination at the bit rate requested by the terminal unit based on the request content received from the request management unit 36.

The output media information is stored in the buffer memories 41 to 4n of the terminal units TG1 to TGn as described above.
After being temporarily stored, the data is decompressed by decompressors 51-5n and reproduced by the media display units 71-7n.

As described above, in the media server system of the first embodiment, when time-continuous information having different bit rates is mixed in the stored information, the time-continuous information corresponding to the bit rate is used. A read request is made at the read amount, and the read time continuous information is transmitted to the terminal at the bit rate. Therefore, the reading efficiency and the transmission efficiency of the stored information are high.

Since the required amount of readout is time-divided so as not to exceed the readout capability of the disk device, each terminal receiving information can transmit desired media information without interruption of video. Can be played.

Although FIG. 1 shows a configuration in which the disk device is divided into a plurality, the number of disk devices may be one.

(Second Embodiment) The media server system of the second embodiment is a system suitable for a case where the stored information includes continuous time information such as audio and video and non-continuous information such as text. is there. In this system, unlike the system of the first embodiment (FIG. 1), a time slot used in the multiple access control device (MAC) 30 of the media server MS is distinguished from a synchronous slot and an asynchronous slot.

The synchronization slot is the same as the time slot in the first embodiment, and a read request for maintaining a constant information transmission amount (band) per unit time is transmitted in this time slot. The number of read requests for each cycle is controlled (that is, bandwidth allocation is performed) so that information is transmitted at a fixed bit rate to the allocated terminal. On the other hand, an asynchronous slot is a time slot in which no bandwidth is allocated. Can be interrupted.

In this asynchronous slot, only the maximum value of the number of block read requests in the time slot is set, and the average value of the number of block read requests in the time slot is not set.
However, the maximum number of block read requests here is set to be equal to the average number N of block read requests of the synchronous slot.

The other structure is the same as the system of the first embodiment (FIG. 1).

The operation of the media server system will be described. The user uses, for example, the terminal unit TG1,
A request for the type of non-time continuous information to be obtained and the reproduction position is input. At this time, the continuity is not required for the non-time continuous information, so that the bit rate is not required.

This request is input to the request management unit 36 of the media server MS, and from the request management unit 36, the request editing unit 35 and MA
It is transmitted to the time slot management unit 32 of C30 and the MTC 22. The time slot management unit 32 that has received this request,
An asynchronous slot or a synchronous slot having a vacant allocation is designated as a time slot for transmitting a non-time continuous information read request. This designation is notified to the bit rate control unit 33, and the bit rate control unit 33 transmits the designation to the request editing unit 35 without calculating the number of block read requests for each cycle.

The request editing unit 35 creates a request designating all blocks of the asynchronous continuous information requested by the terminal unit TG1 and inputs this request to the time slot designated by the time slot management unit 32.

When the time slot is an asynchronous slot, the time slot management section 32 checks whether the number of block read requests transmitted by the time slot exceeds N, and if the number is less than N, the asynchronous slot Are transmitted to the disk device. When the number exceeds N, the request for N out of the block read requests held in the asynchronous slot is transmitted, and for the request exceeding N, there is an asynchronous slot or a free space in the next cycle. A time slot is designated so as to transmit using a synchronization slot. If the time slot is a synchronous slot, it is checked whether the number of block read requests transmitted by the time slot exceeds Nmax, and the same measures are taken as in the asynchronous slot.

When the disk devices 11 to 1m receive the read request for the non-time continuous information, the disk devices 11 to 1m read the non-time continuous information and output it to the media transmission control device 22. Transmit to terminal.

The time slot management section 32 defines a time slot for transmitting a read request for non-time continuous information as a time slot.
An asynchronous slot and a free synchronous slot can be specified at the same time. However, the use of the synchronization slot is only temporary, and the specification for the synchronization slot is
Assignment to a user who wishes to acquire time-continuous information is prioritized.

In this system, when a request for obtaining time-continuous information is made from the terminal unit, the request editing unit 35
In the case where the number of block read requests created in step (1) exceeds the maximum number of block read requests Nmax in the synchronous slot, the time slot management unit 32 determines that the number of block read requests Or assign an asynchronous slot. As a result, the excess requests are transmitted to the disk devices 11 to 1m using the allocated synchronous slots or asynchronous slots, and the isochronism is ensured.

In this time slot assignment,
A request for exceeding Nmax is given priority over a read request for non-time continuous information. By this allocation, the number of block read requests in the asynchronous slot becomes the maximum value N
Is exceeded, if the request for the excess is for non-time continuous information, the request is transmitted using an empty synchronous slot or asynchronous slot in the next cycle, and If the request is for time-continuous information, discard it.

[0066]

As is clear from the above description of the embodiment, the media server system of the present invention can be used in which time continuous information of different bit rates is mixed in stored information, or time continuous information and non-time continuous information are mixed. Even in the case where are mixed, the reading efficiency and the transmission efficiency can be improved, and the band use efficiency can be improved. As a result, information can be provided to more terminals.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a media server system according to an embodiment of the present invention.

FIG. 2 is a diagram showing the number of block read requests of each terminal unit assigned to a time slot of the system;

FIG. 3 is a processing flow when a time slot management unit of the system assigns a terminal to a time slot;

FIG. 4 is a processing flow when the time slot management unit controls the number of block read requests per time slot;

FIG. 5 is a block diagram showing a configuration of a conventional media server system.

FIG. 6 is a diagram showing a relationship between a use time slot of a disk device 1 of a conventional media server system and an operation of each terminal.

[Explanation of symbols]

 MS media server Q1-Qr time slot TG1-TGn terminal 1,11-1m disk unit 2,21,31 switch 22 media transmission control unit 32 time slot management unit 33 bit rate control unit 35 request editing unit 36 request management unit 41 ~ 4n Buffer memory 51 ~ 5n Decompressor 71 ~ 7n Media display

Continuation of the front page (56) References JP-A-8-84128 (JP, A) JP-A-8-88831 (JP, A) JP-A-4-269087 (JP, A) IEICE technical report, SS E91-164 (1992-3-5), Hideki Sakamoto et al., Study of Multimedia Integrated Switching System, p85-90 National Technical Report Vol. 42, No. 5 (1996-10-18), Taihei Yukawa et al., Video Network Server "Video Shower", p. 44-52 IEICE Transactions, Vol. 79-D-II, no. 4 (1996-4-25), Takeshi Omura, et al., Video Server Software-Video Network Server-Design and Implementation Evaluation, pp. 2-6 626-633 (58) Field surveyed (Int.Cl. ⁷ , DB name) H04J 3/00-3/26 H04N 5/93 H04N 7/173

Claims (4)

(57) [Claims] 1. A media server system comprising: a media server that provides compressed and encoded time continuous information and / or non-time continuous information; and a terminal that decompresses and reproduces information provided from the media server. to the media server, and a disk device for dispersing storing information to be provided to the terminal in block units, per cycle from the bit rate at which the terminal requests
Obtain the number of block read requests, and
Time slot so that the number of read requests is positive.
Assigned to the time slot and blocked using the time slot.
Multiple access control means for transmitting a read request to the disk device, and the disk device based on the block read request
The media server system, characterized in that the block of information read out, provided a media transmission control means for outputting requests received continuously or discontinuously to the terminal from. 2. The multiple access control means according to claim 1 , wherein
Dynamically allocates the number of block read requests to
When applying, based on the bit rate required by each terminal
Block read required to be assigned to one time slot
In order to ensure that the total number of requests does not exceed the reference value N,
Specially assign the number of block read requests to lots.
The media server system according to claim 1, wherein 3. The time slot according to claim 1, wherein :
The multiple access control is provided with a distinction from an asynchronous slot.
Means for reading out for the terminal using the synchronization slot.
The number of information blocks to be set is fixed for each terminal.
The block read request for the block being
To the disk device, and using the asynchronous slot,
Blocks where the number of lock units is not fixed for each terminal
A lock block read request is transmitted to the disk device.
3. The media server system according to claim 1, wherein 4. The synchronous access control means according to claim 1 , wherein:
The number of block read requests assigned to the slot is earlier
When the reference value N is exceeded, the block exceeding the reference value N
Block read request of another synchronous slot within the same cycle.
The disk device with Tsu bets or asynchronous slots
The media server system according to claim 3 , wherein the media server system transmits the information .