JP2001092752A - System for distributing picture data and recording medium used for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a picture data distribution system capable of efficiently distributing picture data with appropriate quality in accordance with changes of the network connection environment of a client computer from moment to moment and a recording medium on which its program is recorded. SOLUTION: This system has a 1st computer (image server computer 101) capable of distributing the picture data and one or more 2nd computers (client computer 103) receiving the picture data, and the 1st computer 101 receives a line situation notification message from the 2nd computer 103 and transmits the picture data (picture data extracted among a plurality of pieces of picture data which are preliminarily stored and have different compressibility or picture data compressed with optimum compressibility every time) which are subjected to compressibility being optimum to the communication speed of a line to which the 2nd computer is connected on the basis of the message.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data generation and distribution system for transmitting video streaming data over a network, and more particularly to a data generation and distribution system which is optimal in response to a dynamic change in a network connection environment of a client computer requesting data. The present invention relates to a video data distribution system that realizes efficient video data distribution, and a recording medium on which a program for the system is recorded.

[0002]

2. Description of the Related Art In general video data distribution on a network, a video server computer performs streaming distribution of data corresponding to a data transmission request from a client computer. Normal video data is very large, requiring a large bandwidth on the line. Therefore, conventionally, video data distribution has been performed by performing appropriate compression in consideration of the bandwidth of a line in a limited network.

However, with the recent spread of Internet technology, a number of video distribution systems using the Internet have been devised. When using the Internet, a huge number of computers connected to the Internet and scattered around the world can be client computers. Therefore, the network connection environment of the client computer differs for each client computer.

Therefore, for example, when high-quality (low-compression rate) video data is distributed, a client computer connected to a communication band with a narrow bandwidth cannot receive all the distributed video data. For this reason, when delivering video over the Internet,
In order to enable reception by as many client computers as possible, video data of low quality (high compression rate) adapted to a communication line with a narrow bandwidth has been distributed. In this environment, even a client computer that can receive high-quality video data has to be content with receiving low-quality video data.

[0005] In connection with this problem, a video server prepares a plurality of high-quality and low-quality data of intermediate-form moving image data stored in a storage device in advance, and further requests a client requesting video data. A mechanism has been devised that includes means for acquiring the communication speed of a line to which a computer is connected, and distributes optimal data according to the acquired communication speed.

[0006]

In general, however, the network connection environment of the client computer, that is, the bandwidth changes every moment depending on the degree of line congestion. It detects the network performance (transmission speed) of the client terminal that has a problem, and transmits video data with a compression rate corresponding to the network performance. The quality of the transmission video data (data compression rate ) Is not changed.

An object of the present invention is to provide an image data distribution system capable of efficiently distributing image data of appropriate quality in accordance with a network connection environment of a client computer, that is, an ever-changing bandwidth, and a program therefor. Is to provide a recording medium on which is recorded.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a first computer (preferably an image server computer) capable of streaming distribution of image data and one or more first computers receiving the image data. In the image data distribution system having two computers (preferably client computers), the first computer determines the communication speed of the line to which the second computer is connected based on the line status notification message from the second computer. It is characterized by having an optimal image distribution means for transmitting image data subjected to optimal compression.

The optimum image distribution means includes: (a) a timer for measuring a transmission time, a plurality of image data having different compression ratios, and an internal identification address capable of identifying the content of the image data for each image data. A storage unit for storing data corresponding to a time stamp defining a transmission timing at the time of transmission, and extracting image data with an optimal compression ratio from the storage unit based on a line status notification message from the second computer; Means for distributing the image data of the extracted image data after the internal identification address corresponding to the transmission time measured by the timer, or (b) storage means for holding one image data;
Based on a line status notification message received from the second computer at a predetermined time interval, an image having an optimum compression ratio for the line to which the second computer is connected is obtained from one image data stored in the storage means. Means for dynamically creating and delivering data.

Further, the recording medium of the present invention is capable of computer-readable processing of realizing each means of the first computer (image server computer) and each means of the second computer (client computer) by program code. CD-ROM, DV
D, FD, and other recording media.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described. An image distribution server connected to a network having a function of distributing image data, the image distribution server includes a storage device capable of storing image data, and an unspecified number of clients accessible to the image distribution server It is configured to include a computer.

In creating video data to be distributed, a video server computer creates a plurality of video data from high quality to low quality in a storage device based on the original video data, and sets a time interval for each video data at a fixed time interval. It has a function to add a stamp.

The client computer receiving the video data monitors the state of the received packet during the reception of the video data, and if the lost packet exceeds a certain standard, a sufficient band is secured in the communication line on the client side. If there is no lost packet within a certain reference time, it is determined that a sufficient bandwidth is secured in the communication line on the client side, and the video server computer which is delivering the determination result Means for transmitting to

The video server that has received the above-mentioned determination result selects a video data file of an appropriate quality based on the determination result, and switches the video data file currently being distributed. At this time, a function of referring to the time stamps added to the two video data before and after the switching and starting the distribution of the video data after the switching from the time having the same time stamp as the time when the distribution is stopped Is provided.

According to another aspect of the present invention, there is provided a video server computer connected to a network having a function of distributing video data.
Further, the transmission device has a function of distributing the original video data stored in the storage device while compressing the original video data at a predetermined compression ratio at the time of transmission.

When receiving video data, the client computer monitors the state of the received packet during the reception of the video data, and if the lost packet exceeds a certain standard, a sufficient band is secured on the communication line on the client side. If there is no lost packet for a certain reference time, it is determined that sufficient bandwidth is secured on the communication line on the client side, and the result of the determination is sent to the video server computer being distributed It has a function characterized by a means for performing.

Further, the video server computer having received the above determination result has a function of dynamically changing the compression rate according to the determination result and delivering video data compressed at the changed compression rate. .

By employing the above configuration, the quality of video data to be distributed can be dynamically changed according to the network connection environment of the receiving client computer. As a result, the client computer can always receive the optimized video data apparently without interruption.

In the recording medium of the present invention, the processing performed by the client computer and the processing performed by the video server computer as described above are program-coded and recorded on a computer-readable recording medium such as a CD-ROM, DVD, or FD. Things.

(Explanation of Embodiments) Hereinafter, two embodiments will be described as embodiments of the present invention. FIG. 1 is a block diagram showing a common hardware configuration in the first embodiment and the second embodiment. Although the present invention is applicable to all data (especially image data) that can be compressed and distributed, in the present embodiment, video data (moving image data) will be described as an example.

In FIG. 1, reference numeral 101 denotes a video server computer which creates and distributes video data;
2 is an auxiliary storage device for storing video data, 103 and 103 'are client computers, and 104 is a network environment in which the video server computer 101 and the client computer 103 are connected. In the following description, a case of a client-server system including one server computer and one or more client computers will be described. However, data transfer between two computers from a first computer to a second computer is described. It goes without saying that the present invention can be applied to distribution.

(First Embodiment) First, a first embodiment will be described with reference to FIGS. FIG. 2 is an explanatory diagram of the file structure of the compressed video data file stored in the storage device. In FIG. 2, reference numeral 203 denotes header information of a compressed video data file, 204 denotes an image data file taken up in the present embodiment, and 205 denotes EOF (EOF: Endo).
f File). Reference numeral 201 denotes a time stamp of a compressed video data file which is a feature of the present invention.
02 is the internal identification address of the compressed video data file corresponding to the time stamp 201. Note that the structure of other image files (compressed image file B and compressed image file C) having different compression ratios taken up in this embodiment is also shown in FIG.
Is the same as The internal identification address 202 is provided corresponding to the time stamp 102 for each file, and has a different value depending on the quality (compression ratio) of the file.

FIG. 3 is an explanatory diagram of header information of three types of compressed video data files generated from the same image file and having different compression rates. 10A shows the header information of the low-compression image file A, FIG. 10B shows the header information of the middle-compression image file B, and FIG. 10C shows the header information of the high-compression image file C. . Reference numeral 301 denotes time stamp information, and 302 denotes an internal identification address of the file shown in FIG. 2 corresponding to the index.

FIG. 4 is a diagram for explaining the relationship among three image files having different compression ratios, a time stamp, and an internal identification address. 6A shows the relationship between the low-compression image file A, the time stamp, and the internal identification address, and FIG. 6B shows the relationship between the medium-compression image file B, the time stamp, and the internal identification address, and FIG. Indicates the relationship between the high-compression image file C, the time stamp, and the internal identification address. In this example, for the sake of simplicity, the low-compression image file A shown in FIG. 1A is compressed to half, and the compressed image file A shown in FIG. (C) is shown as a high-compression image file C which has been compressed to / 2. , “Ro”, “ha”, etc. are shown for convenience.

FIG. 5 shows a video server computer 101.
FIG. 5 is a diagram showing correspondences between communication speeds and compressed image files optimized for the communication speeds, which are stored in the storage device. The magnitude relationship of the symbols (m, n) representing the communication speed in FIG. 5 is m <n. As shown in the figure, when the communication speed is low (~
m) The low-quality high-compression image file C is delivered. If the communication speed is high (n-), the high-quality low-compression image file A is delivered.

FIGS. 6 and 7 are flow charts for explaining the operation of the first embodiment. First, the operation of the video server computer 101 that distributes video data will be described in detail with reference to FIG.

In FIG. 6, in response to a data request from the client computer 103, video data in the corresponding storage device (an initial distribution file is set in the system. In the present embodiment, the initial distribution file is "medium compressed image" File B) is started, and the measurement of the delivery time is started (step 601).

When there is a request to receive low-quality data from the client computer 103 (see step 706 in FIG. 7 to be described later) (step 603), according to the correspondence diagram in FIG. The “highly compressed image file C” having inferior grade is determined as a transmission file (steps 604 and 605).

Next, the current distribution time is measured (step 606). In this embodiment, the measuring time at this time is 4 m
s, and the 4 mS start internal identification address of “file B” is “iiii” from the header information shown in FIG.
Is determined (step 607). That is, the images “i” and “ro” are already distributed. The video server computer 101 immediately stops the distribution of the “medium-compressed image file B” that is being distributed, and the images “ha”, “ni”,... Of the “high-compression image file C” from the internal identification address “iiii”.
Start distribution (step 608).

Conversely, a request for receiving high quality data from the client computer 103 (step 7 in FIG. 7 described later)
07 (see step S603: Y).
According to the corresponding diagram, “low-compression image file A”, which is one step higher in quality than “medium-compression image file B” currently distributed, is determined as the next transmission file (steps 604 and 60)
5). The following operation is the same. That is, the video server computer 101 immediately stops the distribution of the “medium compressed image file B” being distributed, and the internal identification address “iiii”
From "low compression image file A" images "ha", "ni",
.. Are started (step 608).

If the current distribution data is "highly compressed image file C" and a lower quality, higher compression image file is requested, there is video data of one step lower quality than FIG. It turns out that it does not. Also, if the current distribution data is “low-compression image file A” and a higher-quality low-compression image file is requested, there is no video data of one-step higher quality than FIG. I understand. In such a case, a message indicating that there is no data is transmitted, and the data distribution at the current time is continued (step 609).

The video server computer 101
Is the end of the video data, that is, "EOF" shown in FIG.
If the distribution has been performed (step 602: Y), the distribution of the data ends.

Next, the operation of the client computer 103 for receiving video data will be described in detail with reference to FIG. In FIG. 7, first, in response to a video data request to the video server computer 101, reception of data transmitted from the video server is started, and at the same time, a lost packet monitoring timer is reset (step 701).

If the number of lost packets exceeds the number already set in the system (step 702: Y), it is determined that a sufficient band is not secured on the communication line on the client computer side, and the low quality data is transmitted to the video server. Is transmitted (step 706). If the number of lost packets does not exceed the number already set in the system (step 702: N), the occurrence of lost packets is constantly monitored (step 703). If the lost packets occur (step 703: Y), The monitoring timer is reset (Step 704).

When the lost packet monitoring timer exceeds a predetermined time set in the system, that is, when a lost packet has not been generated for a predetermined time (step 70).
3: N, 705: Y), client computer 10
It is determined that a sufficient band is secured in the communication line on the third side and that higher-quality data (low-compression data) than the video data currently being received can be received, and a request for high-quality data is sent to the video server computer 101. The message is transmitted (Step 707). In step 708, distribution data of a different quality is received according to the distribution data from the video server computer 101, and at the same time, the lost packet monitoring timer is reset.

Here, when the message of no data shown in step 609 of FIG. 6 is received, according to the message, if there is no low-quality data, the transmission of the low-quality data request message of step 706 is performed. In the case of, the transmission of the high quality data request message in step 707 is stopped. The client computer 1
In the case of receiving the end of the video data up to "EOF" (step 709: Y), the receiving operation ends.

Finally, the video data format will be described in detail. As shown in FIG. 2, the format of the distribution video data in this embodiment is the header information part (20
3) and a data portion (204), and an address for each time stamp is held in the header portion as shown in FIG. When a video server compresses video data, a header portion is generated and added. In addition,
201 and 301, 202 and 30 in FIGS.
2 is the same value.

As described above, according to the first embodiment, high quality (low compression) to low quality (high compression) are used based on original video data.
Until a plurality of video data having different qualities are stored in the storage device of the video server, video data of optimal quality is dynamically switched in response to a distribution request from the client computer according to a reception state in the client computer. While delivering.

(Second Embodiment) In a second embodiment described below, only one type of original video data is stored in a video server, and compression of video data distributed from the server is performed by a client computer. Is dynamically optimized in accordance with the reception state in.

Hereinafter, the processing on the video server side of the second embodiment will be described in detail with reference to FIG. In the figure, first, in accordance with a data request from a client computer, original video data in a corresponding storage device is extracted to a video server (step 801), and compression is performed (an initial compression rate is already set in the system) while performing compression. ) Transmission (step 803). When a low-quality data request or a high-quality data request message is received from the client computer 103 (step 80)
4), change the compression rate (step 805).

The video server computer 101 transmits the video data to the end of the video data (step 80).
2) The distribution operation ends.

The operation of the client computer that receives the video data is the same as that of the first embodiment, and a detailed description is omitted.

Each processing procedure performed by the video server computer and each processing procedure performed by the client computer as described above are recorded on a recording medium such as a CD-ROM, DVD, or FD together or separately, and are put on the market. Can be distributed. The user can easily use the present invention by installing this recording medium on the video server computer and the client computer.

[0044]

As described in detail above, according to the present invention, the video data distributed by the video server is:
It can be dynamically changed according to the network connection environment of the receiving client computer. As a result, the client computer can always receive the optimized video data apparently without interruption.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a common hardware configuration in a first embodiment and a second embodiment of the present invention.

FIG. 2 is an explanatory diagram of a file structure of a compressed video data file stored in a storage device.

FIG. 3 is an explanatory diagram of header information of three types of compressed video data files generated from the same image file and having different compression rates.

FIG. 4 is a diagram for explaining a relationship among three image files having different compression rates, a time stamp, and an internal identification address.

FIG. 5 is a diagram showing a correspondence between a communication speed and a compressed image file optimized for the communication speed, which is stored in the video server computer.

FIG. 6 is a flowchart for explaining the operation of the video server computer in the first embodiment.

FIG. 7 is a flowchart for explaining the operation of the client computer in the first embodiment.

FIG. 8 is a flowchart for explaining the operation of the video server computer in the second embodiment.

[Explanation of symbols]

101: Video server computer (first computer) for creating and delivering video data 102: Storage device for storing video data 103, 103 ': Client computer (second computer) connected to a network 104: Video server Network environment in which a computer and a client computer are connected 105: Program recording medium (CD-ROM) 106: Program recording medium (CD-ROM) 201: Time stamp of compressed file 202: Internal identification address corresponding to time stamp of compressed file 203: File header information of the compressed file 204: File format of the file A taken up in the present embodiment 301: Time stamp information of the compressed file header 302: Of the compressed file header Internal identification address corresponding to the time stamp information

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masaki Nishi 1-16-5 Dogenzaka, Shibuya-ku, Tokyo F-term in Hitachi Information Systems, Ltd. (reference) 5B082 GA01 HA05 5B089 GA11 JA33 JB03 JB22 KA05 KA12 KB06 KB11 KC28 KC53 KC59 KC60 KH28 5C059 KK34 SS09 TA60 TA71 TC21 UA02 UA38 5K030 GA08 HB02 LA07 LC09 LD13 MB13

Claims (5)

[Claims] 1. An image data distribution system having a first computer capable of streaming distribution of image data and one or more second computers receiving the image data, wherein the first computer is the second computer An image data distribution system for transmitting image data compressed optimally to the communication speed of the line to which the second computer is connected, based on the line status notification message from . 2. An image distribution means comprising: a timer for measuring a transmission time; a plurality of image data having different compression ratios; and an internal identification address capable of identifying the content of the image data for each image data. A storage unit for storing data corresponding to a time stamp that defines the transmission timing of the image data; and extracting image data having an optimal compression ratio from the storage unit based on a line status notification message from the second computer. 2. The image data distribution system according to claim 1, further comprising means for distributing image data contents of the extracted image data after the internal identification address corresponding to the transmission time measured by the timer. 3. The optimum image sending means is stored in the storage means based on a storage means for storing one image data and a line status notification message received at a predetermined time interval from the second computer. 2. The apparatus according to claim 1, further comprising means for dynamically creating image data having an optimum compression ratio for a line to which the second computer is connected from one piece of image data and delivering the image data. Image data distribution system. 4. The computer according to claim 1, wherein said first computer is an image server computer, and said second computer is a client computer.
Alternatively, the image data distribution system according to claim 2. 5. A computer-readable recording medium in which processing for realizing each means in the first computer and each means in the second computer according to claim 1 or 2 is stored as a program code. .