JPH09200701A - Multimedia data transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more facilitate jump processing, to accelerate disk access and to improve a data service function by using a form with which only one minimum video reproducing unit is stored at the head of a fixed length area. SOLUTION: A video data storage means 10 stores the minimum video reproducing unit (GOP) of digital video data for multimedia data provision service in the form with which only one GOP is respectively stored at the head of each fixed length area such as 400K bytes, for example. When there are any private data excepting for the GOP such as electronic mail data, for example, a data sending means 11 inserts these data in place of the data stored in the remaining area of 400K bytes and sends them to the side of user as data having the same length as that fixed length area. There are not such private data, the data stored in that fixed length area are sent to the user side as they are.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video-on-demand system and a news-on-demand system for providing a user with video data and audio data of video and news via a network in response to a user's request. The present invention relates to a demand data system or a multimedia data providing system that provides an electronic mail service.

[0002]

2. Description of the Related Art A video-on-demand system that provides video / audio data such as movies via a network and a news-on-demand system that provides video / audio data of news in response to a user's request. Systems for providing electronic mail services and multimedia data providing systems that integrate these systems are being put to practical use.

FIG. 13 shows the flow of video / audio data in a video-on-demand system as an example of such a system. In the figure, the server 1 as the data provider side reads the video / audio data stored in the disk 3 in response to a request from the client 2 who is the user of the data, and reads the data as, for example, an ATM cell. A header is added and the data is sent to the client 2 side via the ATM network. Here, the video data stored on the disc 3 and the MPEG described later.
(Moving Picture Experts Group)
It is assumed to be encoded according to the method.

FIG. 14 is an explanatory diagram of a result of MPEG encoding of video data. The MPEG system is a coding system for efficiently storing video in a digital storage medium. In this coding system, video data is coded into units called digital video minimum units (GOP, group of pictures). Compressed. This GOP is composed of frame data from one I frame to the next I frame, and is encoded in a format in which there is a predetermined number of units, for example, 15 units within a fixed time, for example, 0.5 seconds. Done.

The number of frames in each GOP is determined to be, for example, 15, but the length of the data for one GOP becomes long for an image with a lot of motion, and the video data is MPEG encoder 4 in FIG.
Each resulting GOP encoded by will have a different length.

FIG. 15 shows normal reproduction data in order to realize special reproduction such as reverse reproduction, fast forward, rewind, slow reproduction and slow reverse reproduction in a video-on-demand system as an example of a multimedia data providing system. FIG. 13 is an explanatory diagram of a jump when special reproduction is performed in response to a request from the user when stream data such as reverse reproduction data is held on the system provider side. In the figure, for example, when the user specifies double-speed fast-forward, the jump from the normal reproduction data to the double-speed fast-forward data is performed. When reverse reproduction is requested, a jump to reverse reproduction data is made, and when a slow reproduction request is made, a jump to slow reproduction data is made.

FIG. 16 is an explanatory diagram of a reproduction situation when such a jump is performed. Here, for the sake of simplicity, it is assumed that a jump request is made in response to a skip request from the user side using only the normal reproduction data, and a jump request for two GOPs is made during the reproduction of GOP # 2. . At this time, if all the video data of the # 2 GOP is reproduced and then all the video data of the # 4 is reproduced, the normal reproduction of the video data is performed. For example, immediately after the jump request is made, To the corresponding data position (indicated by the broken line) of # 2, # 2 and # 4
In both cases, not all GOP data is reproduced, and the video data is disturbed.

The disturbance of the video data is caused by the MPEG encoding system. For example, in the MPEG system, three types of coding modes are defined, and the frames corresponding to each mode are called I frame, P frame, and B frame. An I frame is a frame as a result of a normal intraframe coding process, and a P frame is an N-IS.
H.264 as an encoding method in DN. 261 is a frame as a result of interframe predictive coding processing based on the same video signal order as in H.261, and B frame is a frame interpolative predictive coding processing frame that uses frames before and after the video signal for prediction.

In general, encoding is performed in a format in which a plurality of B frames and P frames are inserted between each I frame, and a plurality of portions of one I frame to the next I frame are encoded. The frame is called the video reproduction minimum unit GOP as described above. Therefore, as shown in the lower part of FIG. 16, for example, when all the data of the # 2 GOP is not transmitted to the user side, it is normal on the user side. However, complex abnormalities occur and the image is disturbed.

FIG. 17 is an explanatory diagram of a usage example of a GOP header address table as a conventional example of the special reproduction system for preventing the disturbance of the image when the jump as shown in FIG. 16 is performed. As will be described later, since a GOP header is generally stored at the head of each GOP as data encoded by the MPEG system, when storing MPEG data in a disc, the address of each GOP header is set to GOP. By registering in the header address table, for example, when a jump request to the second is received while GOP # 1 is being reproduced, the reproduction time of 1 GOP is 0.5.
When it is set to seconds, it is understood that it is sufficient to jump to 4 GOP destinations, and by referring to the GOP header address table, GOP #
You can jump to the beginning of 5.

[0011]

As described above, in the prior art, the jump destination is referred to by referring to the GOP header address table in order to prevent the disturbance of the image when the jump is performed in response to the special reproduction request from the user. There was a problem that it was necessary to make a correct decision and it took time to access the disk.

Further, in the multimedia data providing system, for example, when video / audio data is being provided, conventionally, in order to continuously send the data of each GOP together with the audio data to the user side, for example, of the data Even if an e-mail to the user arrives at the provider side of the providing system during transmission and it is necessary to send it to the user side, in general, it should be sent only after the video has finished playing. There is also a problem that the function of the e-mail service is deteriorated because it cannot be done.

It is an object of the present invention to facilitate jump processing during special reproduction, speed up disk access, and improve the functions of multimedia data services including electronic mail services.

[0014]

FIG. 1 is a block diagram showing the principle configuration of the present invention. FIG. 1 is a block diagram of the principle configuration of a multimedia data sending device on the provider side of a multimedia data providing system that provides a multimedia data providing service including video data such as video.

In FIG. 1, a video data storage means 10 is a video reproduction minimum unit (GOP) which is digital video data for a multimedia data providing service, for example, MP.
The minimum unit of video reproduction that is encoded by the EG method and that constitutes a certain fixed number of video data within a certain time period,
Each area of fixed length, for example, 400 Kbytes, is stored in the form of storing only one at the beginning.

The data sending means 11 needs to send to the user the minimum video playback required to provide digital video data in units of the minimum video playback unit in response to a request from the user of the multimedia data. When there is private data other than the unit, for example, electronic mail data, the private data is stored in the fixed length area of the video data storage unit 10 other than the area storing the minimum unit of video reproduction, that is, the remaining 400 Kbytes. The data is inserted in place of the data stored in the fixed area and sent to the user as data of the same length as the fixed length area. If there is no such private data, it is stored in the fixed length area. This data is sent to the user as it is.

As described above, according to the present invention, since the video data is stored in the format in which only one video reproduction minimum unit GOP is stored at the head of each fixed length area in the video data storage means, the user can store the video data. Fast forward, rewind, reverse play from the side,
When there is a request for special reproduction such as slow reproduction or slow reverse reproduction, the data transmission means 11 causes the video data stored in the video data storage means 10, that is, G.
It is easy to use special playback video data on the user side by reading the fixed length area data including OP so that the special playback can be realized in units of the length of the fixed length area and sending it to the user side. You will be able to.

At this time, if there is private data to be sent to the user other than the video / audio data, such as e-mail data, the private data is stored in the GOP in the fixed length area. Data stored in areas other than the existing area, for example, NULL data is inserted instead of, for example, overwritten and sent to the user side as data having the same length as the fixed-length area.
The user can read an e-mail while watching a movie, for example.

[0019]

FIG. 2 is a block diagram showing the overall configuration of a multimedia data providing system including the multimedia data transmitting apparatus of the present invention. This figure has the same overall configuration as that of the conventional example shown in FIG. 13, but various processing sections peculiar to the present invention are provided inside the server 20 and the client 21.

The data registration unit 25 inside the server 20
When video image data is stored in the disk 22, data registration is performed in a format in which one video reproduction minimum unit GOP is stored at the beginning of each fixed length area, as described later.

The data sending unit 26 sends the video / audio data stored in the disk 22 to the client 21 side in response to a request from the client 21 side. Private data such as electronic mail data is packed in the remaining area of the GOP-stored area in the fixed-length area 22 and sent to the client 21 side.

The other service receiving section 27 receives other services such as electronic mail sent from the outside of the system and should be sent to the client 21 side. For example, the data of the electronic mail is stored in the fixed length area by the data sending section 26. The data in the area other than the GOP is overwritten inside and sent to the client 21 side as private data.

The MPEG decoding unit 28 inside the client 21 decodes the MPEG data as the video image data and outputs it to a monitor (not shown). The other service processing unit 29 uses the private data sent from the server 20 side. If there is, the necessary processing is performed according to the content, and the data corresponding to this private data is stored in the fixed-length area GO in the disk 22.
Data previously stored in a storage area other than P, for example, NULL data described later, is ignored.

FIG. 3 is an explanatory diagram of a method of storing MPEG data in the disk 22 by the data registration unit 25 of FIG. In the figure, a GOP header is stored at the beginning of each GOP, and each GOP is stored in a fixed-length area of N bytes in the disk 22 with the GOP header at the beginning. In the remaining area of the fixed length area of N bytes, for example, NULL data is packed in order to equalize the amount of data in the fixed length area and is stored in the disk.

FIG. 4 shows the fixed length area of N bytes of FIG.
The following shows the method of storing MPEG data on the disk when the size is 00 Kbytes. For GOPs other than GOP # 2,
NULL data is stored in the remaining area. As a result, the data length of each GOP itself or the total of GOP and NULL data becomes constant at 400 Kbytes.

FIG. 5 is a diagram for explaining a method of inserting private data to be sent from the server 20 to the client 21 in FIG. In the figure, the private data is a fixed length area in FIG. 3 or 4, and is overwritten on the NULL data stored after the area where the GOP data is stored, and is sent to the client 21 side.

FIG. 6 shows a private data insertion method,
It is explanatory drawing of the example different from FIG. In FIG.
Unlike Fig. 4 and Fig. 4, GOP data is divided into several parts and stored in a format where there are some free spaces in the fixed-length area of n bytes, and private data is distributed and stored in these free spaces. It In this way, the private data is distributed, stored in the data of the length corresponding to the fixed length area, and sent to the client side, whereby the load on the client side can be distributed.

For example, even if it is private data,
When the types are different, such as mail and news, the load on the processing on the client side can be distributed by distributing them. Further, when private data is centrally stored as shown in FIG. 5, there is a possibility that the client side has to interrupt the original service while processing the private data, and the private data is distributed. This can prevent such a thing.

FIG. 7 is an explanatory diagram of a video data registration method in the multimedia data providing system of FIG. The video data is photographed by the AV equipment 31, converted into MPEG data by the encoder 32, and written in the disc 22 by the server 20. At the time of writing, as described with reference to FIG. GOP data is written one by one, and NULL data is packed in the remaining area of the fixed length area.

FIG. 8 is an explanatory diagram of a data transmission method when there is no private data to be transmitted to the client side, that is, a data transmission method only for the video on demand (VOD) service. The MPEG data stored in the disk 22 is read by the server 20, and the data of the fixed length area described in FIG. 3, for example, including NULL data is directly sent to the client 21 side, and GO
The P data is decoded by the MPEG decoder and the movie is watched. NUL sent to client 21
L data is ignored.

FIG. 9 is an explanatory diagram of a data transmission method from the server when there is electronic mail data to be transmitted to the client side. When the electronic mail to be sent to the client 21 arrives at the server 20, the electronic mail data is inserted as private data after the MPEG data read from the disk 22, that is, the GOP data, and sent to the client 21 side. The sent GOP data is decoded by the MPEG decoder and used for watching a movie. Further, the electronic mail data is processed by the other service processing unit shown in FIG. 2, so that the user can read the electronic mail while watching the movie.

FIG. 10 is an explanatory diagram of the data transmission rate from the server in this embodiment. FIG. 1A shows a conventional example. Since it is not necessary to send private data, a plurality of GOPs are successively sent to the client side.

On the other hand, in this embodiment, as shown in FIG. 2B, private data (PD) or NULL
Fixed length data for each GOP, for example, n bytes, is continuously sent to the client side in a format in which data is packed after each GOP.

The transmission rate in FIG. 10 (a) is set to r (bi
t / s) and the data amount to be sent is n ₀ , the same figure (b)
In order to send all GOP data at the same time interval because the amount of data to be sent increases to n ₁ , the transmission rate is

[0035]

[Equation 1]

Therefore, it is necessary to increase the transmission rate as compared with the case of FIG. 10A, but this transmission rate can be made constant regardless of the presence or absence of private data.

FIG. 11 is an explanatory diagram of a jump method for realizing special reproduction in this embodiment. In the present embodiment, GO is placed at the beginning of a fixed-length area of, for example, n bytes.
Since P stores data, it is not necessary to have the GOP header address table as described in FIG.

During normal reproduction, the server reads n from the disc.
Data is read byte by byte and sent to the client side. When a jump request for special playback is received, GO
Since one P, that is, for example, m seconds worth of data has a length of n bytes, the jump destination is calculated and the data is read. This simplifies the scheduling of reads from disk.

For example, if a jump request to 2 seconds later is received during reproduction of GOP # 1, the reproduction time of one GOP data is set to 0.5 seconds, and a jump to 2 seconds later, that is, to jump 4 GOP ahead, In other words, a jump to n × 4 bytes ahead is performed.

FIG. 12 is also an explanatory view of the special reproduction realizing method in the present embodiment, and explanation of the jump method in the case where the MPEG data for double speed reproduction is stored in the disc in addition to the data for normal reproduction. It is a figure. In FIG.
When a double speed reproduction request is issued during the normal reproduction of OP # 4, the video data for double speed reproduction can be provided to the client side by jumping to GOP # 4 of the MPEG data for double speed reproduction. .

[0041]

As described in detail above, when there is private data to be sent to the client side, each GOP data is stored in a fixed length area in the disk in such a form that one data is stored at the beginning thereof. , The private data is inserted in place of the data stored in the remaining area in the fixed length area and sent to the client side so that one service is executed while other services are provided to the client side at the same time. It becomes possible to do. Further, the private data is distributed in the fixed-length area, inserted, and sent to the client side, whereby the processing load on the client side can be distributed. Further, by storing the GOP data on the disc in this way, scheduling of disc access at the time of special reproduction such as fast-forward reproduction is facilitated, which greatly contributes to the improvement of the function in the multimedia data providing system.

[Brief description of drawings]

FIG. 1 is a block diagram showing a principle configuration of the present invention.

FIG. 2 is a block diagram showing a configuration example of a multimedia data providing system for realizing the present invention.

FIG. 3 is a diagram illustrating a method of registering MPEG data on a disc in the present embodiment.

FIG. 4 is an explanatory diagram of a storage method when one piece of GOP data is stored in a fixed-length area of 400 Kbytes.

FIG. 5 is an explanatory diagram (part 1) of a method of inserting private data to be sent to the client side.

FIG. 6 is an explanatory diagram (part 2) of the method of inserting private data to be sent to the client side.

FIG. 7 is an explanatory diagram of a data registration method on the server side.

FIG. 8 is an explanatory diagram of a data transmission method when performing only a VOD service.

FIG. 9 is an explanatory diagram of a data transmission method when an electronic mail service is provided in addition to the VOD service.

FIG. 10 is an explanatory diagram of a video data transmission rate in this embodiment.

FIG. 11 is an explanatory diagram (part 1) of the method for realizing special reproduction in the present embodiment.

FIG. 12 is an explanatory diagram (Part 2) of the method for realizing special reproduction in the present embodiment.

FIG. 13 is a block diagram showing a configuration of a video-on-demand system as an example of a multimedia data providing system.

FIG. 14 is an explanatory diagram of a result of encoding video data according to the MPEG system.

FIG. 15 is an explanatory diagram of various special reproductions in the video-on-demand system.

FIG. 16 is an explanatory diagram of an example of a jump for realizing special reproduction for MPEG data.

FIG. 17 is an explanatory diagram of a GOP header address table for realizing special reproduction.

[Explanation of symbols]

 10 video data storage means 11 data transmission means 20 server 21 client 22 disk 25 data registration section 26 data transmission section 27 other service reception section 28 MPEG decoding section 29 other service processing section 31 AV equipment 32 encoder

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Claims (5)

[Claims] 1. A provider of a multimedia data providing system for providing multimedia data including video data, wherein digital video data for the multimedia data providing service is fixed at a predetermined number. Video data storage means for storing the minimum unit of video reproduction that constitutes the data within the time in a format in which only one unit is stored in each area of fixed length from the beginning of the area, and a user side of the multimedia data. When providing digital video data of the minimum video reproduction unit in response to a request, when there is private data for the user only as data other than the minimum video reproduction unit to be sent to the user, the private data Is stored in an area other than the area in which the video reproduction minimum unit is stored in the fixed length area. Data that is inserted instead of existing data and has the same length as the fixed length area, and sends the data stored in the fixed length area as is when there is no private data. Multimedia data transmission device. 2. The video data storage means divides only one video reproduction minimum unit, stores the first divided data at the beginning of the fixed length area, and stores the fixed length. The second and subsequent divided data are distributed and stored in the remaining area of the area, and the data transmission means divides the private data when the private data is present, and the video reproduction minimum in the fixed length area. 2. The multimedia according to claim 1, wherein the unit is dispersed and inserted instead of the data stored in the region other than the region where the units are dispersed and the data having the same length as the fixed length region is transmitted. Data transmission device. 3. In the multimedia data transmitting apparatus, NUL is provided in an area other than an area in which the video reproduction minimum unit is stored in the fixed-length area of the video data storage means.
The multimedia data transmitting apparatus according to claim 1 or 2, further comprising a data registration unit that stores data in the fixed length area in a format for storing L data. 4. The special reproduction video data including fast-forward, rewind, reverse reproduction, slow reproduction, or slow reverse reproduction of the video digital data can be used by the user in response to a request from the user. In order to achieve this, the data sending means reads out the video playback minimum unit stored in the video data storage means so as to realize the special playback in units of the fixed length area, and sends it to the user side. 3. The multimedia data transmission device according to claim 1, wherein the multimedia data transmission device is a multimedia data transmission device. 5. On the user side of the multimedia data providing system, the minimum unit of image reproduction which is digital image data for multimedia data providing service and which comprises a predetermined number of data within a certain period of time, When only one is stored in each fixed-length area from the beginning of the area, and when there is private data for only the user as data other than the video playback minimum unit, the private data is stored in the fixed-length area. It is inserted in place of the data stored in the area other than the area storing the minimum playback unit, and data of the same length as the fixed length area is sent. When there is no private data, it is stored in the fixed length area. The data of the minimum unit of video reproduction among the data of the fixed length area that is sent as it is. Claim 1 or 2 multimedia data providing system according to the video data decoding means, anda other service processing means for processing the private data that.