JPH1169275A - Video data storage method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video data storage method that efficiently reproduces video images of different bit rates. SOLUTION: Video data of a bit rate that is a multiple of (n) of a basic bit rate are divided into basic blocks, each having a prescribed size, and the basic blocks are assigned periodically to n-sets of partial video files in time series (step 1). The (n) sets of the partial video files are regarded respectively as one video data and stored periodically to plural storage media (step 2). Thus, in the case of reproduction, the video data at a bit rate of a multiple of (n) are read in a flow of time slot similar to reading simultaneously the n-fold of video data at a basic bit rate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of storing video data in a video server for storing and reproducing real-time data such as audio and video data stored on a disk, and more particularly to a method of reproducing data having different bit rates. The present invention relates to a video data storage method for performing the processing efficiently.

[0002]

2. Description of the Related Art In a video server, video data is compression-encoded and stored in a disk of the video server, and the video data is read from a storage medium and distributed to each client in response to a request from a client connected to the video server. I do.

An example of a conventional video server is described in, for example, Japanese Patent Application Laid-Open No. 8-88845. The video-on-demand system described here includes a storage device 501 and a data reading device 502 as shown in FIG.
And memory writing devices 5031 to 503n, buffer memories 5041 to 504n, and memory reading devices 5051 to 5
05n, the terminal devices 5061 to 506n, and the control device 5
07. The storage device 501 includes a plurality of storage media 5011 to 501m such as a magnetic disk, for example.

[0004] The video data stored in the storage device 501 is read out through the data reading device 502, and the buffer memory 50 is read out through the memory writing devices 5031 to 503n.
41 to 504n. The data stored in each of the buffer memories 5041 to 504n is read by the memory reading devices 5051 to 505n,
After being sent to 61-506n and decompressed, it is reproduced and displayed. The control device 507 includes the terminal devices 5061 to 506n.
Storage device 501 based on a distribution request signal input from
And by controlling the data reading device 502, the video data stored in the storage device 501 is read by the data reading device 502, and the buffer memories 5041 to 504n are read.
To be written.

[0005] In this conventional video-on-demand system, video data is divided into predetermined lengths and stored in a storage device 501 periodically. When the number of storage media 5011 to 501m constituting the storage device 501 is four,
FIG. 6 shows the stored state. The video data includes video data blocks VD-001, VD-002,.
It is divided into VD-k and stored periodically in chronological order in the storage media 5011 to 5014.

[0006] The video data stored in the storage device 501 is read out by the data reading device 502, and is finally reproduced and displayed on any one of the terminal devices 5061 to 506n. FIG. 7 is a diagram showing the relationship between the read time from the storage device 501 and the reproduction display time on the terminal device 5061. Video data VD-0 stored in storage medium 5011
01 is read in the video data read time DTread,
The data is stored in the buffer memory 5041. Terminal device 506
In 1, the video data is played back over the video data playback time DTplay. Now, suppose that the video data read time DTread is
Is １ ／ of the video data playback time DTplay, the storage medium 5 within one block of video data playback time.
From 011, four video data blocks can be read.

[0007] Here, a case where video data is reproduced by the terminal device 5061 will be considered. The video data block VD-001 stored in the storage medium 5011 is
2 and passed to the memory writing device 5031. The memory writing device 5031 includes a buffer memory 504
1 is stored. When the data is stored, it is read from the memory reading device 5051 and is reproduced and displayed on the terminal device 5061. Before the end of the reproduction display on the terminal device 5061, the data reading device 502 transmits the next video data VD-0.
02 is read from the storage medium 5012 and stored in the buffer memory 5041 through the memory writing device 5031. The necessary next video data may be stored in the buffer memory before the previous video data has been reproduced and displayed. Therefore, if the video data read time DTread is shorter than the video data reproduction time DTplay, the data reading device 5
02 is capable of reading a plurality of video data from the same storage medium.

FIG. 8 shows a video data reproduction time DTplay.
In the figure, an example of reading out four pieces of video data is shown. A frame that is divided from a certain time for each video data reproduction time DTplay is called a frame, and the frame is referred to as a video data read time DT
Those divided by read are called time slots. There are four types of video data, VD1, VD2, VD3, and VD4. The data reading device 502 sends the video data blocks VD1-001, VD2-001, VD
3-001 and VD4-001 are sequentially read and stored in the buffer memories 5041 to 5044, respectively.
Upon receiving the video data block, the terminal devices 5061 to 5064 expand the video data block and reproduce and display it. Before the reproduction and display of each of the terminal devices 5061 to 5064, the next video data block is read from the storage medium 5012, and the video is reproduced and displayed without interruption.

As described above, when four storage media capable of securing four time slots per frame are used, separate video can be supplied to 4 × 4 = 16 terminal devices as a whole.

[0010]

However, in the conventional video server, one terminal is used for reproducing video information.
Since two time slots are allocated, when simultaneously reading video data of different bit rates, the time slots are uniformly set so as to satisfy the highest bit rate as shown in FIG. In this method, the time slot is configured in accordance with a high bit rate such as the video data B, so that a low bit rate such as the video data A causes waste. For example, if the supplied video data all have a low bit rate like A, half of the disk read processing capacity is wasted.

On the other hand, as shown in FIG. 10, there is a method of controlling the reading of the video data so that the total of each video data reading time DTread falls within one frame. In this case, the readability of the storage medium can be used more efficiently, but there is no difference from the previous method in that a large amount of data must be read from one storage medium at a time for high bit rate video data. For this reason, low bit rate video data, for example, as shown in FIG.
When the video data blocks of B, C, D, E, F, G, and H are uniformly allocated to the time slots, the video data Z of the high bit rate can be obtained even though the readout processing capacity is sufficient. There is a problem that reading cannot be performed. Here, FIG. 11 illustrates a state in which the video data block Z-1 cannot be stored even though each frame has room.

On the other hand, in the invention described in JP-A-8-163072, even in the case of video data of a high bit rate, the video data is divided into blocks of a fixed size and stored in a storage medium in order. The method is taken. According to the method, video data having different bit rates can be provided to the terminal by adjusting the number of blocks read at a time according to the bit rate required by the terminal.

However, in this method, since the blocks of the video data are sequentially allocated to the storage medium,
When video data of different bit rates are reproduced, there is a problem that read control of the storage medium is disturbed.

Here, when reproducing a plurality of video data having the same bit rate, as shown in FIG.
When moving to the next frame, for example, one block is read for each video data from the storage medium 1 in the frame and one block is read for each video data in the second frame. Since the process moves to the next storage medium, there is no disturbance in the read control.

However, according to the invention described in Japanese Patent Application Laid-Open No. H8-163072, when reproducing video data having a double bit rate, as shown in FIG. Two blocks are read from the storage medium-2, and the storage medium-3 and the storage medium-
When moving to the next frame, such as reading two blocks from four, the storage medium to be read moves every third storage medium. Therefore, for example, as shown in FIG. 13, video data blocks A, B, C, and D of a low bit rate are previously allocated in a lump, and the video data Z having a double bit rate is assigned thereto. If assignment is desired, read control will be disrupted. In the example of FIG. 13, since the video data Z has a double bit rate, it is necessary to read two video data blocks per frame. In the first frame, video data blocks A-1, B-1, C-1, D-1, and Z
-1, Z-2 have been successfully assigned to time slots. However, in the second frame, the video data blocks A-2, B-2, C-2, D-2, and Z-3
Can be read successfully, but the video data block Z-4 does not end in the second frame scheduled to be read. In other words, even if a time slot is successfully allocated first, the movement of the time slot differs for each video data having a different bit rate, so that there is a problem that reading cannot be performed within a predetermined frame as time passes.

An object of the present invention is to provide a stable video supply without disturbing the read control of the storage medium even in the reproduction of video data of different bit rates in the video reproduction using time slots. It is an object of the present invention to provide a video data storage method capable of effectively utilizing the reading ability.

[0017]

According to the present invention, video data is divided into basic blocks each having a predetermined size, and the basic blocks are periodically allocated to a plurality of partial video files in a time-series manner. It is characterized in that each video file is regarded as one video data and is periodically stored in a plurality of storage media.

That is, the video data storage method of the present invention
When storing video data with a bit rate that is an integral multiple of the basic bit rate, the amount of data that plays back the video data at the basic bit rate for a certain period of time, that is, the data is divided into basic block units, and the Are stored in a distributed manner as if a plurality of were collected. Therefore, even when video data of different bit rates are simultaneously reproduced, stable video reproduction can be performed without disturbing the read control of the storage medium, and the readability of the storage medium can be effectively utilized.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the meaning of words used in the present invention will be described. In the video server embodying the present invention, the basic bit rate is determined in advance. This is a bit rate serving as a reference for the video data to be stored. For example, if the basic bit rate is set to 3 Mbps, the bit rate of video data that can be stored is 3 Mbps.
s, 6 Mbps, 9 Mbps,... are multiples of the basic bit rate. A block obtained by dividing video data at the basic bit rate for each data amount to be reproduced for a certain period of time is called a basic block. For example, if it is divided every 0.5 seconds, the basic block is about 190 Kbytes.

FIG. 1 shows an outline of the operation in one embodiment of the present invention. The operation of the present invention will be described with reference to the drawings. First, video data is divided into basic blocks, and the data is divided into n partial video files such that the period becomes n in time series (step 1). Where n
Is an integer of 2 or more, and indicates how many times the stored video data is higher than the basic bit rate. For example, when the basic bit rate is 3 Mbps, and when storing 9 Mbps video data, n = 3. FIG. 2 shows an example of division of video data when n = 3. Next, each of the divided partial video files is regarded as one video file and periodically stored in a storage medium (step 2). FIG. 3 shows an example of a state where partial files are stored in four storage media. The partial video file-0 shown in FIG. 2 is periodically stored in storage medium-1, storage medium-2,... As if the partial video file is one video file in FIG. I have. Also, partial video file-1
Are also stored periodically as storage medium-2, storage medium-3,... At this time, the storage of the partial video file may be started from any storage medium. However, in order to enhance the effect of the present invention, it is desirable that a different storage medium be started for each partial video file. However, when the number of partial video files is larger than the number of storage media, storage may be started from the same storage medium.

The allocation and the storage can be performed in parallel. That is, instead of allocating all video data to the partial video file and then storing the data in the storage medium, it is also possible to sequentially store the data of the basic block in the storage medium when the data is received. For example, when dividing video data into a partial video file-0, a partial video file-1, and a partial video file-2, a remainder obtained by dividing a block number by n (= 3) is regarded as a partial video file number, and The storage location of the storage medium can be calculated based on the number and the number of the partial video file.

Next, a method for reading stored video data will be described with reference to FIG. When reading video data having a bit rate three times the basic bit rate (for example, 9 Mbps), the following is performed. Here, the respective partial video files are VD1, VD2, and VD3. Storage medium-1, storage medium-2, storage medium-3 in the first 0.5 seconds
, VD1-1, VD2-1 and VD3-1 are read out for a total of three blocks, and the three blocks are combined in the buffer memory. In the next 0.5 seconds, storage medium-2, storage medium-
3. From storage medium-4 to VD1-2, VD2-2, VD3
-2 and a total of three blocks are read, and the blocks are combined in the buffer memory. By repeating this, 9M
It is possible to reproduce bps video. Looking at only the portion to be read, the operation is the same as that of simultaneously reading the video files of three basic bit rates, so that the operation of the time slot is not disturbed.

The data stored according to the present invention is:
The data can be reproduced using the known data reproducing device shown in FIG.

[0024]

As described above, according to the present invention, when reproducing video data having a bit rate corresponding to an integral multiple of the basic bit rate, reading of the storage medium is performed by reading the video data of the basic bit rate from the storage medium. Since it can be handled in exactly the same way as described above, the read control of the storage medium is not disturbed. For this reason, it is not necessary to provide an extreme margin in the time slot, and it is possible to effectively utilize the readability of the storage medium to the last minute.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an operation in one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a state in which video data is divided into partial video files in the embodiment.

FIG. 3 is an explanatory diagram showing a state in which video data is stored on a disk in the embodiment.

FIG. 4 is an explanatory diagram showing an operation of a time slot for reading video data from a disk in the embodiment.

FIG. 5 is a configuration diagram of a video server using a conventional technique.

FIG. 6 is an explanatory diagram showing that video data is distributed and stored on a plurality of disks in a video server using a conventional technique.

FIG. 7 is a timing chart showing a relationship between a read time from a storage medium in a video server using a conventional technique and a reproduction display time in a terminal device.

FIG. 8 is an explanatory diagram showing a technique for reading four pieces of video data within a reproduction display time.

FIG. 9 is an explanatory diagram showing a first problem when video data having different bit rates are read from a disk using a conventional technique.

FIG. 10 is an explanatory diagram showing a method of reading video data having different bit rates from a disk using a conventional technique.

FIG. 11 is an explanatory diagram showing a second problem in a case where video data having different bit rates are read from a disk using a conventional technique.

FIG. 12 is an explanatory diagram showing a method of reading video data having different bit rates from a disk using a conventional technique.

FIG. 13 is an explanatory diagram showing a third problem in a case where video data having different bit rates are read from a disk using a conventional technique.

[Explanation of symbols]

 , 501m storage devices 5021, 5032, ..., 503n memory write devices 5041, 5042, ..., 504n buffer memories 5051, 5052, ..., 505n memory read devices 5061, 5062, …, 506n terminal device 507 control device

Claims (3)

[Claims] The video data is divided into basic blocks each having a predetermined size, and the basic blocks are periodically allocated to a plurality of partial video files in chronological order. A video data storage method, wherein the video data is periodically stored in a plurality of storage media. 2. The video data storage method according to claim 1, wherein all of the basic blocks are periodically allocated to a plurality of partial video files and then stored in a plurality of storage media periodically. 3. The video data storage according to claim 1, wherein periodic allocation to a plurality of partial video files and periodic storage to a plurality of storage media are performed for each basic block. Method.