Abstract:
An object of the present invention is to provide a content data delivery system that when a user receive a delivery of content data from a plurality of content delivery means having merits and demerits, the user can easily select a favorite content delivery means suitable for himself, and also the content deliverer can prevent troubles.  
     The content data delivery system is characterized by that the content data delivery system comprises a plurality of delivery servers and a delivery route transmission server, the delivery server responding to the download request of a content data and the delivery route transmission server informing a user terminal of the delivery route when a demand for delivering of the content data is made between a content managing server and the user terminal, and the content managing server compares a condition responding to the demand for delivering from the user terminal with a content supply capacity at present by referring to a servicing status of the delivery servers to specify delivery servers capable of supplying the item of content data to the user terminal under the set condition, and transmits delivery route information composed of the specified delivery servers and accounts required for delivery from the delivery servers to the delivery route transmission server and the user terminal, the decided delivery route information being transmitted from the user terminal to the delivery route transmission server.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a system and a method for delivering (supplying) content data such as music data or image data.  
           [0003]    2. Prior Art  
           [0004]    In a content data delivery system using the Internet, a user accesses a delivery site (on any one of a content delivery server, a license accounting server or the other servers) from the user&#39;s terminal, and selects some items of content data among a content list and a data format (a compression mode and so on). When the user selects purchase, the user&#39;s terminal is linked to a license and accounting server to start a payment procedure. The payment procedure is generally performed according to the following order.  
           [0005]    {circle over (1)} Selection of a method of payment  
           [0006]    {circle over (2)} Checking of solvency (inquiring of a database of a settlement organization)  
           [0007]    {circle over (3)} Settling of payment  
           [0008]    After completion of the payment procedure, the license server sends a key to solve the cipher code of the content data to the user. The license and accounting server makes the payment procedure with the settlement organization to distribute the delivery fee to the right holder. The user terminal receiving the key is connected to a content data delivery server to receive the content data.  
           [0009]    Therein, the license and accounting server and the content data delivery server inform a content holder of the record of key and content data. Japanese Patent Application Laid-Open No.11-312175 discloses a technology of delivering music using the Internet and a personal communication line.  
           [0010]    (1) On-demand Type Content Data Delivery  
           [0011]    (a) Delivery is performed by responding to a demand of a user. There are various kinds of communication methods such as a method of using the Internet, a method of directly using a telephone line. However, it is essentially a one-to-one communication method. In a pay content data delivery system, the content data is ciphered, and a key for deciphering is usually downloaded from a Web server, which is called as a license server, after completion of the payment procedure.  
           [0012]    (b) Advantages  
           [0013]    {circle over (1)} The user can receive the content data by on-demand without moving from his own room.  
           [0014]    {circle over (2)} As for the content holder, the initial investment is comparatively small because of no package production.  
           [0015]    (c) Disadvantages  
           [0016]    {circle over (2)} Under the present situation, the telephone line is generally used for the transmission route for delivering the content data, and accordingly a long receiving time is required, which increases expense of the user.  
           [0017]    {circle over (2)} In a case where number of downloads is large, overload of the server and traffic problems of the network are caused to further increase the time for receiving the content data. The content holder may lose his business chance by increasing the waiting time of the users.  
           [0018]    (2) Multicast Type Content Data Delivery  
           [0019]    (a) Content data is delivered to a plurality of specified users (registered users) at a time on the Internet to form a one-to-multitude method. In a pay content data delivery system, the content data is ciphered, and a key for deciphering is usually downloaded from a Web server, which is called as a license server, with a fee.  
           [0020]    (b) Advantages  
           [0021]    {circle over (1)} The cost performance is relatively better when number of receiving times of content data is large because the content data can be delivered to many users at a time.  
           [0022]    {circle over (2)} The waiting time of the user is relatively short if a frequency of delivery is high (interval of delivery is short).  
           [0023]    (c) Disadvantages  
           [0024]    {circle over (1)} Under the present situation, the telephone line is generally used for the transmission route for delivering the content data, but the waiting time of the user is long because a long time is required for receiving the content data by the user terminal.  
           [0025]    {circle over (2)} In a case where the frequency of delivery is too high, burden of the router is increased to decrease performance of the related network. In a case where number of user terminals receiving content data is small, the cost performance is worse.  
           [0026]    {circle over (1)} In a case where the frequency of delivery is low (interval of delivery is long), the waiting time of the user becomes long.  
           [0027]    (3) Broadcast Type Content Data Delivery  
           [0028]    (a) Content data is ciphered and delivered on a CS data broadcast or the like to be received using receivers. In a pay content data delivery system, the content data is ciphered, and a key for deciphering is usually downloaded from a Web server, which is called as a license server, with a fee.  
           [0029]    (b) Advantages  
           [0030]    {circle over (1)} The cost performance is better when number of receiving times of content data is large because the content data can be delivered to many users at a time.  
           [0031]    {circle over (2)} The waiting time of the user is shorter if a frequency of delivery is high.  
           [0032]    (c) Disadvantages  
           [0033]    {circle over (1)} In a case where the frequency of delivery is high, the cost performance is worse if number of user terminals receiving content data is small.  
           [0034]    {circle over (2)} In a case where the frequency of delivery is low (interval of delivery is long), the waiting time of the user becomes long.  
           [0035]    (4) Package Type Content Data Delivery  
           [0036]    (a) Compact disks (CDs) are typical of this content data. The present specification is mainly on the premise that the package type content data delivery is mail-order selling of packages.  
           [0037]    (b) Advantages  
           [0038]    {circle over (1)} In a case where large number of packages are produced, both of expense of the user and expense of the content holder are smaller than those in the on-demand type content data delivery and in the broadcast type content data delivery.  
           [0039]    {circle over (2)} The package type content data delivery is suitable for a long-playing content data (such as an album).  
           [0040]    (c) Disadvantages  
           [0041]    {circle over (1)} Long time is required for manufacturing and delivering the content data packages.  
           [0042]    {circle over (2)} Burden of the content holder is large if the content data packages are left unsold.  
         SUMMARY OF THE INVENTION  
         [0043]    An object of the present invention is to provide a content data delivery system that when a user receive a delivery of content data from a plurality of content data delivery means having merits and demerits as described above, the user can easily select a desirous content data delivery means suitable for himself, and also the content data deliverer can prevent troubles.  
           [0044]    In the present invention, “delivery route information” for sharing a delivery route and a delivery schedule for each item of content data between a user terminal and a content managing server is defined, and a script on a homepage or an apparatus capable of linking to various kinds of delivery servers from the user terminal using the delivery route information is provided and distributed to users. Items of content data to be delivered are uploaded to an on-demand type delivery server, and a multicast type delivery server and a broadcast type delivery server, delivery frequencies of the multicast type delivery server and the broadcast type delivery server are set to initial values (the initial value may differ from content to content).  
           [0045]    The user select an item of the content data and a data format among a content list, and decides to purchase  
           [0046]    After deciding the purchase on the user terminal, the user terminal proceeds to download of the key for decipher. Since there are various kinds of methods of payment such as using credit card, prepaid card etc., the solvency is checked at downloading of the key. If there is no problem, the downloading of the key is allowed. The license and accounting server notifies the content management server of occurrence of the download request of key.  
           [0047]    The content management server compares number of downloads request of the key with a capacity of each of the delivery servers for supplying the specified content at that time, and updates the delivery route information of the content data by increasing and decreasing the on-demand type delivery servers (increasing and decreasing the on-demand type delivery sites), and by increasing and decreasing the delivery frequencies of the multicast type and the broadcast type delivery servers. The update of the delivery route is performed on every downloading of the key, or on every a predetermined number of downloading times of the key, or on every a predetermined time interval. The update of delivery route may be performed by automatically or manually changing the frequency using a numerical formula. The update of delivery route is instantaneously reflected to the “delivery route information” described above.  
           [0048]    In the user terminal, after downloading of the key, downloading of the delivery route information is successively performed. The user selects an appropriate delivery route intentionally or by automatic selection, and then starts downloading of the content data.  
           [0049]    In a case of selecting the on-demand type delivery server, downloading of the content data is immediately started.  
           [0050]    In a case of selecting the multicast type delivery server or the broadcast type delivery server, after a receiving stand-by state, downloading of the content data is started at a delivery start time which is notified by a schedule.  
           [0051]    The present invention is characterized by a content data delivery system in which a plurality of delivery means (delivery means by the Internet (on-demand type and multicast type delivery means), CS data broadcast delivery means (broadcast type delivery means) and mail order delivery means (package type delivery means)) are provide, and the content data can be delivered by a user-desired delivery means.  
           [0052]    The content data delivery system in accordance with the present invention comprises a content managing server, and the content managing server supplies the delivery route information in regard to supplying capacity of each of the delivery means to the user terminal. The user terminal can select a delivery means suitable (short download time, low cost etc.) for purchasing the content data by referring to the delivery route information.  
           [0053]    In detail, the present invention provides the following systems.  
           [0054]    The present invention provides a content data delivery system for delivering a content data to a user terminal according to a demand of a user through a content managing server storing content data and right-holder information, which comprises a plurality of delivery servers and a delivery route transmission server, the plurality of delivery servers delivering the content data when the demand for delivering of the content data is made between the content managing server and the user terminal, the content managing server specifying delivery servers capable of delivering the content data to the user terminal under a condition, the condition being set by comparing a condition responding to the demand for delivering from the user terminal with a content supply capacity at present by referring to a working status of the delivery servers, and transmitting delivery route information to the delivery route transmission server and the user terminal, the deliver route information comprising the information of the specified delivery server and the information of the accounts required for delivery from the specified delivery server, the decided delivery route information being transmitted from the user terminal to the delivery route transmission server.  
           [0055]    The present invention further provides a content data delivery system in which the plurality of delivery servers are a plurality of on-demand type delivery servers, a combination of on-demand type delivery servers and multicast type delivery servers, a combination of on-demand type delivery servers and broadcast type delivery servers, or a combination of these three kinds of delivery servers.  
           [0056]    The present invention further provides a content data delivery system in which the license and accounting server settles account after confirming of the content data being delivered to and received by the user terminal.  
           [0057]    The present invention provides a content data delivery method of delivering a content data to a user terminal according to a demand of a user through a content managing server storing content data and right-holder information, wherein the method comprising the steps of setting a condition responding to the demand for delivering from the user terminal according to a content supply capacity at present by referring to a working status of a plurality of delivery servers between the content managing server and the user terminal; specifying delivery server capable of delivering the content data to the user terminal under the set condition; and transmitting delivery route information comprising the information of the specified delivery server and the information of the accounts required for delivery from the specified delivery server to the user terminal.  
           [0058]    The present invention further provides a content data delivery method in which the plurality of delivery servers are a plurality of on-demand type delivery servers, a combination of on-demand type delivery servers and multicast type delivery servers, a combination of on-demand type delivery servers and broadcast type delivery servers, or a combination of these three kinds of delivery servers. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0059]    [0059]FIG. 1 is a block diagram showing an embodiment in accordance with the present invention.  
         [0060]    [0060]FIG. 2 is a flowchart showing operations of a user terminal, a license and accounting server, a delivery route transmission server and a content managing server.  
         [0061]    [0061]FIG. 3 is a flowchart showing a routine by which a user determines content purchasing.  
         [0062]    [0062]FIG. 4 is a flowchart (1) showing a method of updating a delivery route information.  
         [0063]    [0063]FIG. 5 is a flowchart (2) showing a method of updating a delivery route information.  
         [0064]    [0064]FIG. 6 is a flowchart (3) showing a method of updating a delivery route information.  
         [0065]    [0065]FIG. 7 is an example of delivery route information.  
         [0066]    [0066]FIG. 8 is another example of delivery route information.  
         [0067]    [0067]FIG. 9 is another example of delivery route information. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0068]    An embodiment in accordance with the present invention will be described below, referring to the accompanied drawings.  
         [0069]    [0069]FIG. 1 is a block diagram showing the embodiment in accordance with the present invention. Referring to FIG. 1, content data supplied from a content holder  2  and right holders information of the content data are registered  3  in a content managing server  1 . The content managing server  1  comprises a content storage  4  and a master database (DB)  5 , and the right holder information and the user information are stored in the master DB  5 . The content managing server  1  is connected to an on-demand type delivery server  7 , a multicast type delivery server  8 , a broadcast type delivery server  9 , a delivery route transmission server  10 , a license/accounting server  11  and a package mail order server  12  through a communication network  6  such as an intranet or the Internet. The on-demand type delivery server  7 , the multicast type delivery server  8 , the delivery route transmission server  10  and the license/accounting server  11  are connected to a user terminal  14  through the Internet  13 . The broadcast type delivery server  9  is connected to the user terminal  14  through a satellite broadcast network  15  consisting of a satellite and a parabola antenna satellite broadcast receiver. The package mail order server  12  is connected to the user terminal  14  by a transporting means  16  such as a track.  
         [0070]    In such a content data delivery system, the content data according to a demand of the user is delivered to the used terminal  14  through the delivery servers ( 7 ,  8 ,  9  and  12 ) from the content managing server  1  in which the content data and the right holder information are registered and stored.  
         [0071]    Before start of the content data delivery server, initially, content upload is made to the on-demand type delivery server  7  and may be made to the multicast type delivery server  8  and the broadcast type delivery server  9 .  
         [0072]    When a demand for delivering of content data from the user is made, delivery site change (adding, deleting etc.)  17  are made to the on-demand type delivery server  7 , and delivery schedule change  18  are made to the multicast type delivery server  8  and the broadcast type delivery server  9  depending on the statistical magnitude of the demand.  
         [0073]    The content managing server  1  transmits the information of delivery route and delivery schedule  20  to the delivery route server  10 , and commands the license and accounting server  11  to check status of registration of key and download of key  21 .  
         [0074]    As described above, the content data delivery system comprises the plurality of delivery means. That is, the content data delivery system comprises the delivery means by the Internet (on-demand type and multicast type delivery means), the CS data broadcast delivery means (broadcast type delivery means) and the mail order delivery means (package type delivery means), and the user can receive delivery of the content data from a user-desired delivery means. The content data can be delivered to the user terminal  14  through the plurality of on-demand type delivery means, or the combination of the on-demand type and the multicast type delivery means, or the combination of the on-demand type and the broadcast type delivery means, or the combination of three kinds of delivery means. Further, the package mail order means may be combined.  
         [0075]    As described above, the content data delivery system comprises the content managing server  1 , and the content managing server  1  supplies the delivery route information in regard to supplying capacity of each of the delivery means to the user terminal  14  through the delivery route transmission server  10 . The user can select a delivery means suitable for purchasing the content data in taking conditions such as short download time, low cost etc. by referring to the delivery route information supplied through the user terminal  14 .  
         [0076]    According to the content data delivery system, the content data deliverer can stably supply the content data to the user with avoiding troubles such as an overload of the communication line, spending of a long time in the delivery and so on. On the other hand, the user can select a favorite delivery means in his own convenience, and thereby can obtain the content data without dissatisfaction such as long downloading time, increase in communication fee and so on.  
         [0077]    The change of delivery route is calculated by taking an accounting corresponding to the condition into consideration in addition to the capability of delivering the content data of each of the delivery means.  
         [0078]    The service information supplied to the user through the content data deliver system is classified into basic service and advanced service, and the contents of the services are as follows.  
         [0079]    The service information supplied to the user by the service is as follows.  
         [0080]    [Basic Service] 
         [0081]    1. Content List Database comprising title names, artist names, still pictures of the content data can be seen.  
         [0082]    2. Information on Delivery Routes  
         [0083]    (a) Channel information of on-demand type delivery sites (plural)  
         [0084]    (b) IP addresses and delivery schedules of multicast type delivery sites  
         [0085]    (c) Channel information and delivery schedules of broadcast type delivery sites  
         [0086]    (d) Estimated time until completion of receiving in the cases of using the above delivery means etc.  
         [0087]    [Advanced Service] 
         [0088]    Download information of content data of various kinds of delivery (information on which content data was transmitted when, to whom, by what means etc.) is integrally managed. That is, the constructed system is that identifiers for identifying users (a membership system is employed, and User IDs are issued), identifiers for identifying content data (referred to as Content ID), identifiers for identifying delivery means (referred to as Media ID) etc. are managed as a database, and the DB is updated every content data purchasing by a user. By using the database, the following services can be performed.  
         [0089]    1. Direct mail and E-mail for advertisement can be automatically sent because user&#39;s hobby and taste can be caught as data.  
         [0090]    2. Cash-back service (by electronic money, web money etc.).  
         [0091]    (a) It is possible to service cash-back to a user purchasing a content data when the user purchases another content data. The cash-back is reflected to the database.  
         [0092]    (b) It is possible to service cash-back to a user purchasing a content data (such as a single) when the user purchases a group of content data (an album) including the content data previously purchased. (by this service, people purchasing a single are motivated to purchase an album.)  
         [0093]    (c) It is possible to service cash-back to a user purchasing an item of content data when the user purchases in a different data format which was previously purchased by the user the content data.  
         [0094]    Various kinds of services can be performed by combining the package mail order type delivery in addition to the deliveries described above. In this case, delivery information on the package mail order (cost, the appoint date of delivery etc.) is added to the “delivery route information”. When the package mail order is selected, the procedure is shifted to a normal Internet mail order routine.  
         [0095]    1. Service of distributing music in a limited delivery term until the appoint date of delivery with a low price or free to a user purchasing a package.  
         [0096]    2. Service of distributing studio-drained music (full chorus may be unnecessary) in a limited delivery term until the on-sale date with a low price or free to a user making an advanced order of purchasing a new music package.  
         [0097]    [0097]FIG. 2 is a flowchart showing operations of the user terminal  14 , the license and accounting server  11 , the delivery route transmission server  10  and the content managing server  1 . When the user decides purchasing of a content data (S 1 ), the user searches the delivery route information on the user terminal  14  (S 2 ). After receiving the delivery route information (S 3 ), the user selects a favorite delivery route (S 4 ), and notifies the selected delivery route (S 5 ). Then, the user receives a key for decipher the content data, and receives the content data from each of the content data delivery servers (S 7 ), and acknowledges completion receipt of the content data (S 8 ), and thus the procedure is completed (S 9 ). The license and accounting server receives the delivery route information by the step (S 5 ) of the notifying delivery route (S 11 ), and notifies the content managing server of the delivery route (S 12 ). Successively, the license and accounting server transmits the key (S 13 ). The user terminal receives the key in the step S 6 . The license and accounting server receives the completion receipt in the step S 8  of the acknowledging receipt of content data to complete the payment procedure (S 14 ), and settles the account with a settlement organization (S 15 ), and repeats the steps of S 11  to S 15 .  
         [0098]    The delivery route transmission server receives searching in step S 2  of the searching delivery route information to perform delivery route information service (S 21 ) for supplying the delivery route information. At performing this service, conditions such as an estimated waiting time until completion of download or delivery, an estimated communication cost and quality of the content data (compression method, transfer rate) for each of all the delivery routes are transmitted.  
         [0099]    The content managing server monitors status of each of the content data delivery servers (acquiring of the estimated waiting time at supplying the content data, the estimated cost, the quality of the content data etc.) (S 31 ), and adds number of download times of key (per unit time) by receiving the notification of the delivery route to the content managing server in the step S 12  (S 32 ), and changes the delivery route and updates the delivery route information (S 33 ), and transmits the results to the delivery route transmission server in the step  21 .  
         [0100]    Different from the procedure shown in the above-mentioned flowchart, there is a case in which the order of the receiving of the content data and the payment procedure is inverse.  
         [0101]    Although the terms of payment in most cases are payment by credit card, bit cash or prepaid card such as web money, payment into the bank is admitted before the key is distributed by E-mail.  
         [0102]    [0102]FIG. 3 is a flowchart showing a routine by which a user determines content data purchasing. The user searches a piece of music on Web site (S 41 ), and decides to purchase the piece of music (S 42 ). The user acquires the delivery route information (S 43 ). An estimated waiting time until completion of download or delivery, an estimated communication cost and qualities of the content data (compression method, transfer rate) for each of all the delivery routes are displayed. The user selects a favorite delivery route (S 44 ), and judges whether or not on-demand delivery is selected (S 45 ). If “yes”, the user receives the key (S 46 ), and connects to the download site (S 47 ), and receives the content data (S 48 ), and acknowledges receipt of the content data (S 49 ), and thus the procedure is complete (S 50 ). If “no” in the step  45 , the user judges whether or not multicast delivery is selected (S 51 ). If “yes”, the user receives the key and a muliticast IP address (S 52 ). The user judges whether or not delivery of the content data is started (S 53 ). If “yes”, the procedure proceeds to the step  48  to receive the content data. If “no”, the step S 53  is repeated.  
         [0103]    If “no” in the step S 51 , the user judges whether or not broadcast delivery is selected (S 54 ). If “yes”, the user receives the key, a broadcast channel identifier etc. (S 55 ), and judges whether or not delivery of the content data is started (S 56 ). If “yes”, the procedure proceeds to the step  48  to receive the content data. If “no”, the step S 56  is repeated. If “no” in the step S 54 , the user judges whether or not package mail order delivery is selected (S 57 ). If “yes”, the procedure proceeds to mail order delivery routine (S 58 ). If “no”, the procedure proceeds to the other specific routines (S 59 ).  
         [0104]    [0104]FIG. 4 is a flowchart showing a method of updating the delivery route information, and shows an example in which the delivery routes are two routes of the on-demand type delivery and the multicast type delivery, and there is no change in the delivery frequency in the multicast type delivery.  
         [0105]    A cycle (n−1) and a cycle (n−2) are assumed in the precedent side with respect to a time point A, and a cycle (n), a cycle (n+1) and a cycle (n+2) are assumed in the following side.  
         [0106]    A delivery route change program is started to calculate an estimated value ET(n+1) of the total download demands in the cycle (n+1) from numbers of the total download RT in the cycle (n−1) and the cycle (n−2) (S 61 ), and it is judged whether or not multicast type delivery is performed in the cycle (n−1) (S 62 ). If “no”, it is judged whether or not the estimated value ET(n+1) exceeds an on-demand delivery threshold ThD (S 63 ). If “yes”, it is judged whether or not there is a vacancy in multicast delivery list of the cycle (n+1) (S 64 ). If “yes”, this content data is added to a multicast type delivery list of the cycle (n+1) (S 65 ), and the delivery route information of the cycle (n+1) is updated (S 66 ) to complete the delivery route change (S 67 ), and then the processing proceeds to the next cycle. If “no” in the step S 63  or in the step S 64 , the processing directly proceeds to the step S 66 .  
         [0107]    If “yes” in the step S 62 , an estimated value EM(n+1) of number of multicast type delivery receiving times in the cycle (n+1) is calculated from numbers of downloads (receiving times) RM(n−1) and RM(n−2) in the cycles (n−1) and (n−2) using the following conditional equation (S 68 ). That is, If the number of downloads of multicast type delivery RM(n−2)=0, the estimated value of number of multicast type delivery receiving times EM(n+1)=RM(n−1). else EM(n+1)=RM(n−1)+2*(RM(n−1)−RM(n−2)). Then, it is judged whether or not the estimated value EM(n+1) exceeds the multicast delivery threshold ThM (S 69 ). If “no”, this content data is deleted from the multicast type delivery list of the cycle (n+1) (S 70 ). Then, the processing proceeds to the step S 66 . If “yes”, the processing directly proceeds to the step S 66 .  
         [0108]    It is assumed that the multicast type delivery server delivers all the content data registered in the delivery list during one cycle according to a determined schedule.  
         [0109]    An example of the multicast type delivery list is as follows.  
                                                   TIME   CONTENT NO.                           01:00:00   xxxxxx           01:04:23   aaaaaa                      
 
         [0110]    In this case, duplication of the content number is not allowed.  
         [0111]    The estimated value of download demand is estimated from actual values measured in past several cycles. Although there are various estimating methods, the estimation in the above example is executed by the simplest method of using actual values measured in past two cycles.  
         [0112]    At the time point A of the figure, the estimated value ET(n+1) of the total download demands during the cycle (n+1) is estimated from total number of downloads (RT(n−2) and RT(n−1)) during the cycle (n−2) and the cycle (n−1). That is,  
           ET ( n+ 1)= RT ( n− 1)+2*( RT ( n −1)− RT ( n −2)).  
         [0113]    The estimated value is compared with a threshold, and the multicast type delivery list during the cycle (n+1) is updated (that is, the delivery schedule of the cycle (n+1) is determined).  
         [0114]    The reason why the multicast type delivery list during the cycle (n+1) is updated is that the multicast type delivery schedule during the cycle (n) has been already transmitted to the user terminal before the time point A.  
         [0115]    Therein, the threshold may be a value which cause an overload on the on-demand type servers.  
         [0116]    [0116]FIG. 5 is a flowchart showing a method of updating the delivery route information, and shows an example in which the delivery routes are two routes of the on-demand type delivery and the multicast type delivery, and there is change in the delivery frequency in the multicast type delivery.  
         [0117]    Number of delivery times of the multicast type delivery during the cycle (n) is put to Hm(n). The delivery route change program is started to calculate an estimated value ET(n+1) of the total download demands in the cycle (n+1) from numbers of the total downloads RT in the cycle (n−1) and the cycle (n−2) (S 71 ), and it is judged whether or not multicast type delivery is performed in cycle (n−1) (S 72 ). If “no”, it is judged whether or not the estimated value ET(n+1) exceeds on-demand delivery threshold ThD (S 73 ). If “yes”, it is judged whether or not there is a vacancy in multicast delivery list of cycle (n+1) (S 74 ). If “yes”, it is set that Hm(n+1)=1 (S 75 ), and the delivery route information of the next cycle is updated (S 76 ) to complete the delivery route change (S 77 ), and then the processing proceeds to the next cycle. If “no” in the step S 73  or in the step S 74 , the processing directly proceeds to the step S 76 .  
         [0118]    If “yes” in the step S 72 , it is judged “whether or not ET(m+1) exceeds the threshold ThD” (S 78 ). If “yes”, an estimated value EM(n+1) of number of multicast type delivery receiving times in the cycle (n+1) is calculated from numbers of downloads (receiving times) RM(n−1) and RM(n−2) in the cycles (n−1) and (n−2) using the following conditional equation (S 79 ). That is,  
         “if  RM ( n −2)=0 , EM ( n+ 1)= RM ( n −1).  
         [0119]    else EM(n+1)=RM(n−1)+2*(RM(n−1)−RM(n−2))”. Then, EM(n+1) is compared with the product of the multicast threshold ThM and Hm(n−1) (that is, ThM·Hm(n+1)) (S 80 ). If EM(n+1)&gt;&gt;ThM·Hm(n+1), it is judged “whether or not there is a vacancy in the multicast delivery list of the next cycle (n+1)” (S 81 ). If “yes”, it is set that Hm(n+1)=Hm(n+1)+1 (S 82 ), and the processing procedds to the step S 76 . If EM(n+1)=ThM·Hm(n+1) in the step S 80 , or if “no” in the step S 81 , it is set that Hm(n+1)=Hm(n−1) (S 83 ), and the processing proceeds to the step S 76 . If EM(n+1)&lt;&lt;ThM·Hm(n+1) in the step S 80 , it is set that Hm(n+1)=Hm(n−1)−1 (S 84 ), and the processing proceeds to the step S 76 .  
         [0120]    In the above-mentioned case, duplication of the content number is allowed, and frequency of content data delivery can be changed.  
         [0121]    The threshold ThD may be numbers of download which is judged to cause an overload on the on-demand type servers.  
         [0122]    The threshold ThM is a number of receivers of multicast type delivery by which a sufficient profit can be obtained by once of the multicast delivery.  
         [0123]    [0123]FIG. 6 is a flowchart showing a method of updating the delivery route information, and shows an example in which the delivery routes are three routes of the on-demand type delivery, the multicast type delivery and the broadcast type delivery, and there is no change in the delivery frequency in both of the multicast type delivery and the broadcast type delivery.  
         [0124]    The delivery route change program is started to calculate an estimated value ET(n+1) of the total download demands in the cycle (n+1) from numbers of the total download RT in the cycle (n−1) and the cycle (n−2) (S 91 ), and it is judged whether or not multicast delivery is performed in cycle (n−1) (S 92 ). If “no”, it is judged whether or not the estimated value ET(n+1) exceeds the on-demand delivery threshold ThD (S 93 ).  
         [0125]    If “yes”, it is judged whether or not there is a vacancy in multicast delivery list of the cycle (n+1) (S 94 ). If “yes”, this content data is added to a multicast type delivery list of cycle (n+1) (S 95 ), and the processing proceeds to the step S 99  (to be described later). If “no” in the step S 93  or in the step S 94 , the processing directly proceeds to the step S 99 .  
         [0126]    If “yes” in the step S 92 , an estimated value EM(n+1) of number of receiving times of the multicast type delivery of the cycle (n+1) is calculated from numbers of download (receiving times) RM(n−1) and RM(n−2) in the cycles (n−1) and (n−2) (S 96 ), and it is judged whether or not the estimated value EM(n+1) exceeds the multicast delivery threshold ThM (S 97 ). If “no”, this content data is deleted from the multicast type delivery list of the cycle (n+1) (S 98 ).  
         [0127]    If “yes” in the step S 97 , the processing directly proceeds to the step S 99 .  
         [0128]    In the step S 99 , it is judged whether or not broadcast type delivery is performed in the cycle (n−1). If “no”, it is judged that whether or not the estimated value ET(n+1) exceeds the on-demand threshold ThD (S 100 ). If “yes”, it is judged whether or not there is a vacancy in the broadcast type delivery list of the cycle (n+1) (S 101 ). If “yes”, this content data is added to the broadcast type delivery list of the cycle (n+1) (S 102 ). Then, the delivery route information of the cycle (n+1) is updated (S 103 ), and the delivery route change is completed (S 104 ), and the processing proceeds to the next cycle. If “no” in the step S 100  and the step S 101 , the processing directly proceeds to the step S 103 .  
         [0129]    If “yes” in the step S 99 , an estimated value EB(n+1) of number of broadcast type delivery receiving times in the cycle (n+1) is calculated from numbers of download (receiving times) RB(n−1) and RB(n−2) in the cycles (n−1) and (n−2) using the following conditional equation (S 105 ). That is, if the number of download of multicast type delivery RB(n−2)=0, the estimated value of number of broadcast type delivery receiving times EB(n+1)=RB(n−1). else EB(n+1)=RB(n−1)+2*(RB(n−1)−RB(n−2)). Then, it is judged whether or not the estimated value EB(n+1) exceeds the broadcast delivery threshold ThB (S 106 ). If “no”, this content data is deleted from the broadcast type delivery list of the cycle (n+1) (S 107 ), and the processing proceeds to the step S 103 . If “yes” in the step S 106 , the processing directly proceeds to the step S 103 .  
         [0130]    [0130]FIG. 7 is an example of the delivery route information presented to the user which is shown by a simulation of the content data delivery system.  
         [0131]    (Conditions)  
         [0132]    1. A case of two delivery routes of the on-demand type and the multicast type corresponding to FIG. 4 and FIG. 5 is assumed.  
         [0133]    2. It is assumed that content data capable of being download in 10 minutes are delivered through two routes of the on-demand type and the multicast type.  
         [0134]    3. It is assumed that delivery is performed once in 240 minutes when the multicast type delivery is performed, and the download time is 10 minutes.  
         [0135]    4. It is assumed that an estimated communication cost can be acquired by inquiring DBs (databases) of a provider and a communication line (carrier) company in contract with the user. (The communication cost including the line fee and the provider fee is calculated in a rate of 10 yen per minute (rounding up the fractions).  
         [0136]    In the case shown in FIG. 5, the communication line may be connected so as to match with delivery time when the schedule of the multicast type delivery is known.  
         [0137]    [0137]FIG. 8 is another example of the delivery route information presented to the user which is shown by a simulation of the content data delivery system. In this case, quality of content data is also taken as a parameter.  
         [0138]    (In This Case, Quality is Taken as a Parameter)  
         [0139]    (Conditions)  
         [0140]    1. A case of two delivery routes of the on-demand type and the multicast type corresponding to FIG. 4 and FIG. 5 is assumed.  
         [0141]    2. Two kinds of qualities A, B are provided for one item of content data, and it is assumed that the volume of the quality A data uses two times of that of the quality B data. For example, in a case of music, it is assumed that sound quality corresponding to a CD can be obtained by the quality A, and sound quality corresponding to FM broadcast can be obtained by the quality B.  
         [0142]    3. It is assumed that content data are delivered through two routes of the on-demand type and the multicast type.  
         [0143]    4. It is assumed that in the on-demand type delivery, the download time takes 10 minutes for the quality A data and 5 minutes for the quality B data when the server and the communication line are not busy.  
         [0144]    5. It is assumed that two kinds of deliveries of the quality A data and the quality B data are performed once in 240 minutes when the multicast type delivery is performed, and the download time is 10 minutes for the quality A data and 5 minutes for the quality B data.  
         [0145]    6. It is assumed that an estimated communication cost can be acquired by inquiring DBs (databases) of a provider and a communication line (carrier) company in contract with the user. The communication cost including the line fee and the provider fee is calculated in a rate of 10 yen per minute (rounding up the fractions).  
         [0146]    [0146]FIG. 9 shows another simulation example.  
         [0147]    (Conditions)  
         [0148]    1. A case of three delivery routes of the on-demand type delivery, the multicast type delivery and the broadcast type delivery corresponding to FIG. 6 is assumed. (The communication cost including the line fee and the provider fee for the on-demand type delivery and the multicast type delivery is calculated in a rate of 10 yen per minute (rounding up the fractions).  
         [0149]    2. It is assumed that content data capable of being download in 10 minutes through the Internet and 1 minute through data broadcast are delivered through three routes of the on-demand type, the multicast type and the broadcast type.  
         [0150]    3. It is assumed that delivery is performed once in 240 minutes when the multicast type delivery is performed, and the download time is 10 minutes.  
         [0151]    4. It is assumed that delivery is performed once in 480 minutes when the broadcast type delivery is performed, and the download time is 1 minute. It is assumed that the broadcast receiving fee is 10 yen per minute.  
         [0152]    5. It is assumed that an estimated communication cost other than the broadcast can be acquired by inquiring DBs (databases) of a provider and a communication line (carrier) company in contract with the user.  
         [0153]    In the case of the example shown in FIG. 9, the communication line may be connected so as to match with delivery time when the schedule of the multicast type delivery is known. Further, the communication line may be disconnected after receiving the key when the schedule of the broadcast type delivery is known.  
         [0154]    As described above, according to the present invention, content data can be delivered by a user-desired delivery means, and a delivery means suitable for purchasing content data can be selected on a user terminal by referring to delivery route information. Further, since the user can select the most suitable delivery means in matching with his own convenience, content data can be obtained without dissatisfaction in delivering system of the content data.  
         [0155]    Further, there is an advantage that the content data deliverer can stably deliver the content data to the user with avoiding troubles such as an overload of the communication line, spending of a long time in the delivery and so on.