WO2005043403A1

WO2005043403A1 - Method and system for transmitting partitioned data for streaming service on low speed channel

Info

Publication number: WO2005043403A1
Application number: PCT/KR2004/002302
Authority: WO
Inventors: Kwang-Jun Kim
Original assignee: Immertec Co., Ltd.
Priority date: 2003-11-03
Filing date: 2004-09-09
Publication date: 2005-05-12
Also published as: KR20050042377A

Abstract

There is provided a data division method and system for streamimg service capable of solving both transmission speed problem and copy problem in an existing moving emage transmission simultaneously, at the time that need of multimedia communication increases with a growth of a very high speed communication network. The inventive data division transmission method of streaming service via low speed channel, the method comprising the steps of: dividing contents original data into data for precedence downloading and data for real time streaming according to a present rule; transmitting the data for precedence downloading in non-real time by on-line or off-line; transmitting the data for real time streaming by real time streaming service; and synthesizing the data for precedence downloading with the data for real time streaming, to recovery and reproduce the original data. According to the present invention, it is possible to offer a high streaming service at a low speed channel, while maintaining security.

Description

METHOD AND SYSTEM FOR TRANSMITTING PARTITIONED DATA FOR STREAMING SERVICE ON LOW SPEED CHANNEL

TECHNICAL FIELD The present invention relates to a data transmission technology; and, more particularly, the present mvention is directed to a data division method and system for providing a streaming service of high quality via a low speed channel as well as protecting contents.

BACKGROUND ART In general, various contents and services have been provided on on-line as Internet develops. In case of Internet TV, NOD service, on-line education, etc., data is transmitted in real-time using streaming technology. However, if amount of data is bulky as in moving image, it needs a high speed channel to provide the streaming service. This requires a high price equipment to offer a superior quality service, and thus, makes much communications costs occurred. Further, if there is used a low speed channel, much buffering time is needed, thereby deteriorating the quality. Moreover, existing streaming services provide real time service by using a high price equipment unreasonably, although most services do not require real time service. In other words, it is not required to provide real time service for those services, except for services that are sensitive to delay time as phone service. As such, in most Internet real time streaming services, for example, movies, which are currently on services, have been done in real time although they may be replaced with reservation services. Thus, the existing services are reactive to be sensitive to circumstance of Internet and also result in a problem of payment of high cost. On the other hand, most contents protection technologies proposed to date are methods that insert or encrypt specific codes, without damaging inherent characteristics of original data. Typical technology of theses methods is watermarking which inserts any invisible marks into literary work. Specifically, this watermarking, that is a technology that inserts marks into original data, to not recognize to the naked eye, is widely used in various applications as well as copyright protection. There are many watermarking methods based on characteristics of insertion detection, which depend on many mathematical operations since invisible marks are inserted to original data. However, it is known that a most large problem of these contents protection technologies is that there exists a risk that original data may be exposed by reverse engineering since all information is stored in only one file.

DISCLOSURE OF THE INVENTION To solve the problems as mentioned above, therefore, it is an object the present invention to provide a data division transmission method and system which is capable of offering a high quality streaming service, even at a low speed communication channel by transmitting only data for streaming over a streaming channel after transmitting data for downloading in advance over another path, based on a decision as to whether contents to be transmitted are for downloading or for streaming. Another object of the present invention is to provide a data division transmission method and system which is capable of, after transmitting them over different paths, based on a decision as to whether contents to be transmitted are for downloading or for streaming, protecting illegal copy and usage of contents by not reproducing, if only one file is received. In accordance with one aspect of the present invention, there is provided a data division transmission method for streaming service via a low speed channel, said method comprising the steps of: dividing original data of contents into data for precedence downloading and data for real time streaming according to a preset rule; transmitting the data for precedence downloading in non-real time by on-line or off-line; transmitting the data for real time streaming by real time streaming service; and synthesizing the data for precedence downloading with the data for real time streaming, to recovery and reproduce the original data. In accordance with another aspect of the present invention, there is provided a data division transmission system for streaming service via a low speed channel, said system comprising: a streaming server for transmitting streaming files into which original file of contents is divided; a downloading server for transmitting downloading files into which the original file is divided; and a user device for obtaining downloading files by connecting to the downloading server and receiving streaming files by connecting to the streaming server, and synthesizing the downloading files with the streaming files to thereby reproduce the original file. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects and features of the instant mvention will become apparent from the following description of preferred embodiments taken in conjunction with the accompanying drawings, in which: Fig. 1 depicts a block diagram showing the whole concept of division transmission in accordance with a preferred embodiment of the present invention; Fig. 2 is an example of static division that divides original file into files with constant block size in accordance with the present invention; Fig. 3 provides an example of dynamic division that divides original file into files with variable block size in accordance with the present invention; Fig. 4 shows an example of dividing image screen into two based on position information in accordance with the present mvention; Fig. 5 illustrates a conventional arrangement of pixels for forming image screen; Fig. 6 presents an example of separating each pixel value from the image of Fig. 5 in accordance with the present invention; Fig. 7 offers a diagram showing the concept of reproducing files that have been static divided in accordance with the present invention; Fig. 8 is a diagram showing the concept of reproducing files that have been dynamic divided in accordance with the present invention; Fig. 9 depicts a functional block diagram showing the whole configuration that provides Internet services in accordance with the present invention; and Fig. 10 shows an operational flow chart performing in the synthesis player shown in Fig. 9.

BEST MODES FOR CARRYING OUT THE INVENTION Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. As shown in Fig. 1, a data division transmission system in accordance with the mvention comprises a division section 110 for dividing contents file at server side, a transmission section 120 for transmitting divided contents files via different chamiels, and a reproduction section 130 for synthesizing and reproducing contents files received at user side. In a preferred embodiment of the invention, each of contents division, transmission, and reproduction will be independently and sequentially described in detail for the purpose of comprehension. 1. Contents division It enables contents division to identify data for streaming transmission for transmitting data to be transmitted in a streaming manner (hereinafter, called "streaming file"), and data for precedence downloading for transmitting in a precedence downloading manner (hereinafter, called "precedence file"). This contents division is classified by file division technique for dividing original file generated by coding sources such as static image, moving image, audio, text, graphic, etc., according to a certain rule, and source division teclmique for dividing the sources themselves according to the certain rule. In a preferred embodiment of the invention, it is assumed that there will be illustrated and explained image as source; and source division will be called image division below. Specifically, the file division technique enables a file division processor 112 to divide original file 111 that is data to be transmitted into two division files Ilia and 111b based on a predetermined division rule 113. It is classified by static division and dynamic division, which can be used regardless of type or form of the original file 111 and are based on the division rule 113. The static division technique predefines block size of divided files constantly, and then uniformly divides the original file on the basis of the predefined block size. Here, the block size of the divided files may be changed based on applications environment. This static division teclmique has advantages that time taken for division can be reduced and reproduction process can be simplified since it divides the original file by a constant size. The dynamic division technique functions to divide the original file into divided files with variable block size. In this case, there is a necessity of any information on variable block size at the time of reproduction. That is, at the reproduction time, divided file 1, divided 2, and block size data on divided files should be given to produce the original data and reproduce it through the use of a reproduction program. Thus, the dynamic division technique is capable of enhancing the contents protection by managing block size information on divided files separately. Fig. 2 shows a process of dividing the original file by the static division teclmique in accordance with the present invention. Referring to Fig. 2, if size of each block of the first divided file Ilia was set to

"La", and size of each block of the second divided file 111b was set to "Lb", then the static division teclmique alternately and sequentially divides the original file 111 into odd blocks 1, 3, 5, 7, 9 having size of "La", and even blocks 2, 4, 6, 8, 10 having size of "Lb", thereby obtaining the first divided file Ilia having blocks of La size and the second divided file 111b having blocks of Lb size. Thus, the original file 111 comprising blocks 1 to 10 are divided into the first divided file Ilia of odd blocks 1, 3, 5, 7, 9 having size of "La", and the second divided file 111b of even blocks 2, 4, 6, 8, 10 having size of "Lb". Here, if size of the last divided block 10 is smaller than that of Lb or La, null data is filled therein. Fig. 3 shows an example of dynamic division technique that divides the original file into blocks of variable size in accordance with the present invention. hi the dynamic division technique, size of each divided block is not constant. As methods of deteπmning size of each divided block, there are first-size decision after- division that first defines size of each block to be divided as those in a division information table, divides the original file based on the division information, defining table values until division of the original file has been completed as division information, and manages them along with the divided files, and first-division after-size calculation that creates division information file by calculating size of each divided block while dividing the original file in random period, without defining size of each divided block in advance. For example, if the first-size decision after-division method is applied to the technique as illustrated in Fig. 3, block size of the first divided file is defined as Lai, La2, La3, La4,..., and block size of the second divided file is defined as Lbl, Lb2, Lb3, Lb4,..., in order to make dynamic division of the original file 111 into the first divided file Ilia and the second divided file 111b. Thereafter, the original file 111 is divided into a first block file 1 of Lai size and then into a second block file 2 of Lbl size, and sequentially further divided in the same mamier, to form the first divided file Ilia by collecting blocks 1, 3, 5, 7, 9 having size of Lai, La2, La3, La4,..., and the second divided file 111b by collecting blocks 2, 4, 6, 8, 10 having size of Lbl, Lb2, Lb3, Lb4,... Here, if current block is the last block 10 while dividing the original file 111, null data is filled in the remainder thereof to have the required size and then the block size information Lai, Lbl, La2, Lb2,..., created until that time is managed as the division information file 114. Meanwhile, if the first-division after-size calculation method is applied to the teclmique as illustrated in Fig. 3, while the original file 111 is sequentially divided into the blocks 1, 3, 5, 7, 9 of the first divided file Ilia and the blocks 2, 4, 6, 8, 10 of the second divided file 111b according to a random period, the division infonnation file 114 is generated by calculating each block size and using calculated block sizes, Lai, Lbl, La2, Lb2,... As mentioned above, if the original file is divided according to the first- division after-size calculation method, it is not necessary to add null data even to the last divided file. If the dynamic division is used regardless of the method applied, security on the contents can be enhanced since it is not possible to reproduce correctly although the first divided file I lia and the second divided file 111b are obtained if there is no division information 114 representing each block size information. The image division method may be used properly when data to be transmitted is image data, and may be classified by division method based on sequence information of pixels and method of dividing internal bit information of pixels. The pixel sequence-based division method depends on the sequence of pixels in the whole image as in Fig. 4. Referring to Fig. 4, if original image 401 is arranged in 1, 2, 3,...N for horizontal, and 1, N+l, 2N+1,..MN+1 for vertical, a first divided image 401a includes odd pixels of the original image 401 and the second divided image 401b contains even pixels of the original image 401. By doing so, each divided image can be reduced to half of the original in size. The images divided so are coded by coding process; and they are sorted by precedence and streaming files and then transmitted over different paths. The pixel internal information-based division method is as follows. First of all, in case where image screen is represented by pixels, it may be displayed as n x m pixel plane as shown in Fig. 5; and, if a pixel is represented as 8 bits for each of R, G, B, in color, it may be displayed as 24 bits as shown in PI of Fig. 6. Referring to Fig. 6, in case image with color tone of 24 bits is divided according to the present invention, data

PI with 8 bits for each of R, G, B may be divided into lower 4 bits Pl_l, and upper 4 bits

Pl_2. As descried earlier, the original image can be divided into the first divided file with lower bit pixel information Pl_l, and the second divided file with upper bit pixel information Pl_2. Here, it should be noted that bit criteria for division may be set differently according to usage environment.

2. Transmission The transmission section 120 pre-downloads one of the two files Ilia, 111b, e.g., precedence file 111b, divided from the original file 111 over download channel 122. If the size of divided files is different, it may be convenience that file of a relatively large size out of the divided files may be set as precedence file and be pre-downloaded to provide a high quality media service in a low grade communication line. And, the remaining file (i.e., streaming file Ilia) is transmitted over streaming channel. As method for transmitting the precedence file to user side in advance, there are a method of allowing the user to download in advance on on-line and another method for distributing using CD-ROM, etc. onto off-line. Further, by transmitting, after dividing the original file into the precedence file and the streaming file, them over different paths, it is not possible to reproduce the files although they are hacking or the distributed precedence file is copied, thereby protecting the pre-downloaded file from reverse engineering. As mentioned above, the remaining file (streaming file) transmitting in real time can be used as encryption key. 3. Reproduction Process of reproducing, in the reproduction section 130, the precedence file 111b' and streaming file Ilia transmitted respectively after dividing is somewhat different according to division method. That is to say, the prior art image reproduction method is only a method of receiving and reproducing real time streaming from network or reproducing file stored in PC; and, but, the inventive reproduction method recoveries and reproduces the original file by unifying the precedence file 111b' pre-stored in computer and the streaming file Ilia received in real time from network in a file synthesis processor 131. This inventive reproduction method is new method that is not used previously, and is method that is capable of providing a high quality streaming service, even over low speed communications channels. Fig. 7 shows the concept of reproducing static divided files as shown in Fig. 2 in accordance with the present invention. Referring to Fig. 7, in the first divided file 601 with constant block size of La divided according to the process shown in Fig. 2 and second divided file 602 with constant size of Lb, the second divided file 602 having the relatively large size is pre- downloaded and stored; and thereafter, it is synthesized with the first divided file 601 downloaded in real time from the streaming server 603, to display synthesized file. In other words, the second divided file 602 pre-downloaded is combined with the first divided file 601 that is the real time streaming data, thereby recovering the original file 111 ', and this recovered original file is then provided to the reproduction processor 132, to reproduce in the same as the original data. Fig. 8 is a diagram showing the concept of reproducing files that have been dynamic divided as shown in Fig. 3 in accordance with the present invention. Referring to Fig. 8, in the first divided file 701 with different block sizes of Lai, La2, La3, La4,., divided according to the process shown in Fig. 3 and the second divided file 702 with different block sizes of Lbl, Lb2, Lb3, Lb4,., the second divided file 702 having the relatively large size is pre-downloaded and stored; and thereafter, it is synthesized with the first divided file 701 downloaded in real time from the streaming server 704, to display the synthesized file. Here, in order to synthesize the dynamic divided files, division information file 703 is needed along with the first divided file 701 and the second divided file 702, wherein it is desirable that the division information file is transmitted in whole at service start time through a streaming server 704. If the division information file 703 is received, then the second divided file 702 pre-downloaded is synthesized with the first divided file 701 that is the real time streaming data based on the division information, thereby recovering the original file

111 ', and this recovered original file is then provided to the reproduction processor 132, to reproduce the original data. Fig. 9 is a functional block diagram showing the whole configuration that provides Internet service in accordance with the present invention, and Fig. 10 is an operational flow chart of synthesize player shown in Fig. 9. Referring to Fig. 9, a service site 810 capable of providing a good streaming service, even via a low quality channel, in accordance with the invention, comprises a first data base (DB1) 812 for storing streaming file, a streaming server 814 for transmitting the streaming file in a streaming manner pursuant to user's request, a second database (DB2) 816 for storing the precedence file, and a download server 818 for pre- downloading the precedence file. Here, the service site 810 divides the original file into the precedence file for pre-downloading and the streaming file for real time streaming transmission by the contents division process as explained above, and stores them in the corresponding DB. Further, when necessary, the precedence file can be made in the form of CD-ROM 836 and distributed to the user. And, although it is not shown in detail in the drawings, the service site 810 may contain hardware and software such as web server, mail server, subscriber management DB, router, etc. which need in conventional Internet site. In addition, each user 830 includes a computer (PC, notebook, PDA, etc.) 832 that embeds a synthesis player 834 for synthesizing and reproducing the precedence file and the streaming file in accordance with the present invention, wherein the precedence file can be pre-downloaded from the download server 818 of the service site 810 over Internet or distributed in the form of CD-ROM 836. And, the user 830 receives and pre-stores the precedence file of target contents in the computer 832, prior to getting streaming service on desired contents by comiecting to the service site 810. Under this circumstance, if the user connects to the streaming server 814 through the service site 810, the synthesis player 834 is executed according to the procedure shown in Fig. 10. The synthesis player 834 may be driven first prior to connecting to the streaming server 810. Referring to Fig. 10, the user connects to the streaming server 814 and then selects desired contents (SI, S2). The synthesis player 834, if the contents are selected, confirms whether there exists the precedence file of the contents by searching the local computer 832 of the user (S3). If the searched result indicates the absence of the precedence file, the process of the invention provides error message such as "The reproduction is impossible since there is not the precedence file of the contents. Please select again after connecting to www.xxx.vw and downloading the precedence file or select other contents." (S5) But, if there is the precedence file, the inventive process opens the precedence file and performs loading (S4). Thereafter, the process of the invention receives the streaming file of the contents from the streaming server 814 and synthesizes it with the precedence file, to thereby recovery the original file and reproduce the recovered file to provide it as image and/or audio (S6-S9). Here, in case where the precedence file is synthesized with the streaming file, a proper synthesis method may be used based on the division manner; and thus, information on the division manner and block size information of the divided files should be contained in the precedence file or the streaming file, or be provided from the streaming server 814. In particular, in case of the dynamic division method, the division information file should be transmitted from the streaming server 814. The process of the invention repeatedly perfoπns the steps of receiving the streaming file and synthesizing it with the precedence file until the desired contents are all reproduced.

INDUSTRIAL APPLICABILITY Currently, showing various services widely provided over Internet, most services tend to be offered in real time streaming method, regardless of the characteristics of service data (contents). For this, the service provider must comprise high price system; and it also needs high quality channel between the provider and the user. However, the present invention divides the original file of contents to be provided as streaming service into precedence file for downloading and file for streaming in advance. Then, the present invention allows the precedence file to be transmitted to the user in advance over other path, not real time, and also allows only the streaming file to be sent in real time streaming method. As a result, it is possible to provide a high quality streaming service even under poor channel environments. In particular, although one file is exposed on any transmission path after transmitting the divided files to the user over different paths, the present invention is capable of protecting from illegal copy of contents or the usage by making it to be not reproduced. In other words, as mentioned above, the prior art contents protection technology has the drawbacks that since it protects the contents by concealing other data in the original data or by encryption technique, the original data may be recovered by reverse engineering. In contrast, the present invention divides the contents into two incomplete files, making the recovery of the original data by the reverse engineering impossible. While the present invention has been shown and described with respect to the particular external circuit power control method for a reverse data service, it will be apparent to those skilled in the art that many changes and modifications may be made without departing from the scope of the invention as defined in the appended claims and those equivalent thereto.

Claims

1. A data division transmission method for streaming service via a low speed channel, said method comprising the steps of: dividing original data of contents into data for precedence downloading and data for real time streaming according to a preset rule; transmitting the data for precedence downloading in non-real time by on-line or off-line; transmitting the data for real time streaming by real time streaming service; and synthesizing the data for precedence downloading with the data for real time streaming, to thereby recovery and reproduce the original data.

2. The method of claim 1, wherein the dividing step divides the original file into streaming file having blocks with a first fixed size and file for downloading having blocks with a second fixed size.

3. The method of claim 1, wherein the dividing step divides the original file into streaming file having blocks with first variable sizes and file for downloading having blocks with second variable sizes other than the first variable sizes, and produces division information file representing size information of each block.

4. The method of claim 3, wherein the dividing step divides the original file based on a first-size decision after-division technique that first defines size of each block to be divided as that in division information table, divides the original file based on the division information, and manages along with the divided files, after defining table values till division of the original file has been completed as division information file.

5. The method of claim 3, wherein the dividing step is based on a first- division after-size calculation technique that creates the division information file by calculating size of divided files while dividing the original file in random period, without defining size of divided files in advance.

6. The method of claim 4 or 5, wherein the transmitting step transmits the divided information files over a streaming channel.

7. The method of claim 1, wherein, when servicing a part of the divided files in real time streaming, the streaming transmitting step varies ratio of a real time streaming buffer according to transmission rate of a network.

8. A data division transmission system for streaming service via a low speed channel, said system comprising: a streaming server for transmitting streaming files into which original file of contents is divided; a downloading server for transmitting downloading files into which the original file of contents is divided; and a user device for obtaining downloading files by connecting to the downloading server and receiving streaming files by connecting to the streaming server, and synthesizing the downloading files with the streaming files, to thereby reproduce the original file.

4.

9. The system of claim 8, wherein the user device checks whether there are downloading files if specific contents are selected after a comiection to the streaming server, and outputs an error message if there are no downloading files, the user device reading the downloading files if there are the downloading files and synthesizing them with the streaming files.

10. The system of claim 8, wherein the transmitting system further comprises means for dividing the original file of contents into the streaming files and the downloading files.

11. The system of claim 10, wherein the dividing means divides the original file of contents into the streaming file having blocks with a first fixed size and a file for downloading having blocks with a second block size.

12. The system of claim 10, wherein the dividing means divides the original file into the streaming file having blocks with first variable sizes and file for downloading having blocks with second variable sizes other than the first variable sizes, and produces division information file representing size information of each block.