Abstract:
A music data distribution system for distributing music data to an external device connected to a network, comprises: a storage device that stores first music data; a receiver that receives a music data distribution request from the external device connected to the network, the music data distribution request comprising at least music data identification information and music data quality information; a reading device that reads the first music data from said storage device in accordance with the music data identification information; a quality converter that converts the first music data into second music data having a quality different from the first music data in accordance with the music data quality information; and a transmitter that transmits the first or the second music data to the external device in accordance with contents of the music data distribution request.

Description:
[0001]    This application is based on Japanese Patent Application 2000-341899, filed on Nov. 9, 2000, the entire contents of which are incorporated herein by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    A) Field of the Invention  
           [0003]    The present invention relates to a music data distribution system, and more particularly to a music data distribution system for converting music data and distributing the converted music data to an external device via a network.  
           [0004]    B) Description of the Related Art  
           [0005]    There is a music data distribution system wherein music data of a musical instrument digital interface (MIDI) format, an MPEG Layer 3 (MP3) format or the like capable of being reproduced by electronic musical instruments, computers and the like can be purchased by downloading from a server via a network such as the Internet, instead of purchasing music data recorded in a recording medium such as a CD-ROM at stores.  
           [0006]    In such a data distribution system, the music data is likely to be prepared in only one quality. Therefore, a user who just needs a low quality data sometimes needs to buy a high quality data for an expensive price.  
           [0007]    The quality of music data includes not only the sound quality of reproduced music, but also the amount of information contained in the music data. The information contained in the music data includes score data corresponding to the music data, data for controlling a tone generator, and the like. In this specification, music data containing a larger amount of information is called music data of a high quality or high quality music data.  
           [0008]    Music data is often sold separately for mobile phones and electronic musical instruments. Generally, music data for mobile phones and electronic musical instruments is recorded in different file formats, so that one cannot reproduce music data for another.  
           [0009]    Therefore, the user should purchase music data that can be reproduced by an apparatus owned by the user. The user is required to search reproducible music data from a large amount of music data. It is also necessary for each user apparatus to access in a manner specific to the apparatus a home page selling reproducible music data.  
           [0010]    If music data of various file formats and qualities compatible with various types of apparatuses is to be sold at one home page, a number of files are required to be prepared for each music piece and the memory capacity of the server increases.  
           [0011]    If the number of types (qualities and file formats) of music data to be dealt with one home page increases, it becomes more difficult to select reproducible music data by using an apparatus owned by a user, leaving a risk of diminishing purchase desire.  
         SUMMARY OF THE INVENTION  
         [0012]    An object of the present invention is to provide a music data distribution system capable of generating music data corresponding to a plurality types of qualities and presenting them to users, by changing the contents or an amount of information of pre-stored music data.  
           [0013]    Another object of the present invention is to provide a music data distribution system capable of distributing music data having a quality matching a user terminal type and reception environment, at a reasonable price.  
           [0014]    According to one aspect of the present invention, there is provided a music data distribution system for distributing music data to an external device connected to a network, comprises: a storage device that stores first music data; a receiver that receives a music data distribution request from the external device connected to the network, the music data distribution request comprising at least music data identification information and music data quality information; a reading device that reads the first music data from said storage device in accordance with the music data identification information; a quality converter that converts the first music data into second music data having a quality different from the first music data in accordance with the music data quality information; and a transmitter that transmits the first or the second music data to the external device in accordance with contents of the music data distribution request.  
           [0015]    According to another aspect of the invention, there is provided a A music data distribution system for distributing music data to an external device connected to a network, comprises: a storage device that stores first music data; a receiver that receives a music data distribution request from the external device connected to the network, the music data distribution request comprising at least music data identification information and device identification information; a searching device that searches the first music data from said storage device in accordance with the music data identification information; a quality determiner that determines a quality of said music data which can be reproduced by said external device; and a transmitter that transmits information displayed on a display of said external device for promoting purchase of said music data with the quality determined by said quality determiner to said external device.  
           [0016]    It is possible to generate music data corresponding to a plurality type of qualities and presenting them users, by changing the contents of music data prepared beforehand.  
           [0017]    It is also possible to distribute music data having a quality matching a user terminal type and reception environment, at a reasonable charge.  
           [0018]    It is also possible to generate music data corresponding to file formats reproducible by a plurality type of apparatuses, by changing the file format of music data prepared beforehand. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    [0019]FIG. 1 is a block diagram showing an example of the structure of a music data distribution system  1  according to an embodiment of the invention.  
         [0020]    [0020]FIG. 2 is a block diagram showing the specific hardware structure of a computer PC constituting a user terminal  4  or management server  2 .  
         [0021]    [0021]FIG. 3 is a flow chart illustrating a process to be executed by CPU  14  of the management server  2  and user terminal  4  of the music data distribution system of the embodiment.  
         [0022]    [0022]FIGS. 4A to  4 D are diagrams showing examples of various display windows used for purchasing music data.  
         [0023]    [0023]FIG. 5 is a diagram showing request information and terminal information.  
         [0024]    [0024]FIGS. 6A to  6 C are diagrams showing examples of music data, a correspondence table and a conversion table.  
         [0025]    [0025]FIG. 7 is a block diagram showing main functions of the music data distribution system  1  having the management server  2 , network  3  and user terminal  4 .  
         [0026]    [0026]FIG. 8 is a diagram showing an example of the conversion table. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0027]    [0027]FIG. 1 is a block diagram showing an example of the structure of a music data distribution system  1  according to an embodiment of the invention. This system  1  has a data distribution apparatus (management server)  2  and a user terminal  4  interconnected by a communication network  3  such as the Internet or communication lines. The user terminal  4  may be a data communication terminal  4   a  for wired communications or a portable communication terminal (portable data terminal)  4   b  for wireless communications.  
         [0028]    The data distribution apparatus  2  is, for example, a World Wide Web (WWW) server on the Internet constituted of a computer PC or the like, and stores a large amount of music data as will be later described. This data distribution apparatus  2  provides pay services for distributing stored music data to the user terminal  4  upon request from the user.  
         [0029]    The user terminal  4  may be the data communication terminal  4   a  or portable data terminal  4   b , and can be connected to the communication network  3  such as local area networks (LAN), the Internet, and telephone lines. The user terminal  4  is connected to the management server  2  via the communication network  3  to download desired music data from the management server  2 . If the portable data terminal  4   b  is used, this terminal is connected to a wireless base station  6  via a wireless communication channel  5 , and the base station  6  is connected to the management server  2  via the communication network  3 .  
         [0030]    The user terminal  4  as a client transmits a command (music data request information) for requesting to download music data or the like to the management server  2  via the communication network  3 . Upon reception of this music data request information, the management server  2  distributes the requested music data or the like to the user terminal via the communication network  3 . The user terminal  4  receives the music data or the like and stores it in an external storage unit  16  or a RAM  13  shown in FIG. 2 to be described later, to thus complete the download of music data or the like.  
         [0031]    As will be later detailed, when the music data is downloaded, the management server  2  can convert the file format of stored music data into the file format reproducible at the user terminal, and can change the contents or information amount (quality) of music data so as to satisfy user desire.  
         [0032]    [0032]FIG. 2 is a block diagram showing the specific hardware structure of a computer PC constituting the user terminal  4  or management server  2 . The structure of the computer PC will be described by taking as an example the computer PC used as the data communication terminal  4   a  (user terminal  4 ).  
         [0033]    Connected to a bus  11  are a detector circuit  17 , a display circuit  19 , a RAM  13 , a ROM  12 , a CPU  14 , an external storage unit  16 , a communication interface  25 , an MIDI interface  23 , a timer  15  and a tone generator circuit  21 .  
         [0034]    A user can enter necessary information such as a music program name and singer name to be downloaded, by using an operation unit (input means)  18  connected to the detector circuit  17 . For example, the operation unit  18  may be any unit capable of outputting a signal corresponding to a user input, such as a mouse, a keyboard for entering characters and the like, a keyboard for musical performance, a joy stick, and a switch. A plurality of operation units may be connected.  
         [0035]    The display circuit  19  is connected to a display  20  and can display various informations on the display  20 .  
         [0036]    The external storage unit  16  has an interface and is connected via the interface to the bus  11 . The external storage unit  16  may be a floppy disc drive (FDD), a hard disc drive (HDD), a magneto optical disc (MO) drive, a compact disc read-only memory (CD-ROM) drive, a digital versatile disc (DVD) drive or the like. The external storage unit  16  may store a plurality of music data sets, a program for realizing the functions of the embodiment, and the like.  
         [0037]    RAM  13  has flags, registers, buffers and working areas for CPU  14  for storing music data such as MIDI performance data. ROM  12  can store various parameters, control programs, the program for realizing the embodiment functions, and other data. The programs and other data are not required to be stored duplicately in the external storage unit  16 . CPU  14  performs calculations or controls in accordance with the control programs stored in ROM  12  or external storage unit  16 .  
         [0038]    The timer  15  connected to CPU  14  and the bus  11  supplies CPU  14  with a main clock signal, interrupt timing and the like.  
         [0039]    Music data and the like are stored in the external storage unit  16 , RAM  13  or ROM  12 . Music data can be transferred to and from the external via the communication interface  25 .  
         [0040]    The MIDI interface  23  is used for connection to other musical instruments, audio apparatuses, computers or the like, and can transmit/receive at least MIDI signals. The MIDI interface  23  is not limited only to a dedicated MIDI interface, but it may be other general interfaces such as RS-232C, universal serial bus (USB) and IEEE1394. In this case, data other than MIDI message data may be transmitted/received at the same time.  
         [0041]    The electronic musical instrument  24  is an audio apparatus, musical instrument or the like connected to the MIDI interface  23 . The type of an electronic musical instrument is not limited only to a keyed instrument, but other types may also be used such as a stringed instrument, a wind instrument and a percussion instrument. The electronic musical apparatus is not limited only to an electronic musical instrument of the type that the components thereof such as a tone generator and an automatic performance apparatus are all built in one integrated body, but these components may be discrete and interconnected by communication devices such as MIDI and various networks. The tone generator circuit  21  generates tone signals in accordance with supplied MIDI signals or the like, and supplies the generated tone signals to a sound system  22 . The sound system  22  includes a D/A converter and speakers, and converts supplied digital tone signals into analog tone signals to produce sounds.  
         [0042]    The tone generator circuit  21  may be of any type, such as a waveform memory type, an FM type, a physical model type, a harmonics synthesis type, a formant synthesis type, and an analog synthesizer type having a voltage controlled oscillator (VCO)+a voltage controlled filter (VCF)+a voltage controlled amplifier (VCA).  
         [0043]    The tone generator circuit  21  is not limited only to those made of hardware, but may be realized by a digital signal processor (DSP) and a micro program, by a CPU and a software program, or by a sound card.  
         [0044]    One tone generator circuit may be used time divisionally to form a plurality of sound producing channels, or a plurality of tone generator circuits may be used to form a plurality of sound producing channels by using one tone generator circuit per one sound producing channel.  
         [0045]    The control programs, program realizing the embodiment functions and the like may be stored in a hard disc (HDD) of the external storage unit  16 . By reading the control programs and the like from the hard disc to RAM  13 , CPU  14  can perform operations similar to those when the control programs and the like are stored in ROM  12 . In this case, addition, version-up and the like of the control programs and the like can be made easy.  
         [0046]    The control programs, program for realizing the embodiment functions and the like may be stored in a CD-ROM. The control programs, program for realizing the embodiment functions and the like can be copied from CD-ROM to the hard disc. In this case, addition, version-up and the like of the control programs and the like can be made easy.  
         [0047]    The communication interface  25  is connectable to the communication network  3  such as a local area network (LAN), the Internet, and a telephone line. The server is connected via the communication network  3  to download the control programs, the program realizing the embodiment functions, and the like from the server into the external storage unit  16  such as HDD or RAM  13 .  
         [0048]    If the computer PC is used as the portable data terminal  4   b , the MIDI interface  23  and external storage unit are not necessarily required. In this case, the communication interface  25  is required to be connectable to the communication channel by wireless communications. For example, the communication interface  25  can connect a wireless communication channel for mobile phones. The portable data terminal  4   b  is not limited only to a mobile phone, but it may be any type capable of connecting the communication network  3  by wireless communications.  
         [0049]    If the computer PC is used as the management server (data distribution apparatus)  2 , the tone generator circuit  21  and the like are not necessarily required. The hardware structure is generally similar to that of the user terminal  4 . In this case, a plurality of original music data MO sets are stored in the external storage unit  16  of the management server  2 , as shown in FIG. 6A.  
         [0050]    The original music data MO is the data for reproducing a music program, which data is generated and recorded in the file format reproducible by n electronic musical instrument. The original music data MO is the data having a plurality of parts and the highest quality. The data of the highest quality contains reproduction parts corresponding in number to the maximum number of parts (e.g.,  128  parts) which parts can be reproduced by a high quality music reproducing apparatus, a fine pitch change by pitch-bend data, a tone color change by tone color number data, score data for displaying a detailed score of all parts, and the like. The data of the highest quality may further contain fine setting of tone color contents by parameter setting, a fine tempo change by tempo data, a code progress designation by a code sequence, a fine velocity (sound volume) by velocity data and the like.  
         [0051]    In this embodiment, particular data is removed from the original music data MO of the highest quality for electronic musical instruments to thereby create music data MD of various qualities. The file format is converted into the file format reproducible by cellar phones or the like.  
         [0052]    [0052]FIG. 3 is a flow chart illustrating a process to be executed by CPU  14  of the management server  2  and user terminal  4  of the music data distribution system according to the embodiment of the invention. The left part shown in FIG. 3 illustrates the process to be executed by CPU  14  of the user terminal  4 , and the right part illustrates the process to be executed by CPU  14  of the management server  2 . Broken line arrows show a flow of data or the like to be transferred between the user terminal and management server via the communication network  3  (FIG. 1).  
         [0053]    The process on the user terminal side to be executed by CPU  14  of the user terminal  4  shown in the left side of FIG. 3 will be described first.  
         [0054]    At Step SA 1  the process on the user terminal side starts to thereafter advance to next Step SA 2 .  
         [0055]    At Step SA 2  a user enters a uniform resource locator (URL) of the management server  2  to connect the user terminal to the management server  2  via the Internet (communication network)  3  and download a music data purchase home page display file from the management server  2 . As the music data purchase home page display file is downloaded, this home page containing a music program information input window such as shown in FIG. 4A to be described later, is displayed on the display  20  (FIG. 2). Thereafter, the flow advances to next Step SA 3 .  
         [0056]    The music data purchase home page display file is, for example, an HTML format file that can be displayed by a usual Internet browser. This file displays the music program information input window such as shown in FIG. 4A and prompts the user to enter music data request information RI (FIG. 5) necessary for selecting music data or the like. The details of the music program information input window shown in FIG. 4A will be later given.  
         [0057]    At Step SA 3  the music data request information RI entered by the user as well as terminal information TI specific to the terminal stored beforehand in ROM  12  or the external storage unit  16  of the user terminal, is transmitted to the management server  2 . Thereafter, the flow advances to next Step SA 4 .  
         [0058]    The music data request information RI and terminal information TI are integrated as one data block as shown in FIG. 5. The music data request information to be entered by the user contains the information for identifying music data desired to be downloaded, such as a music program name and a singer name of the music data. The terminal information TI is stored beforehand in ROM  12  or the external storage unit  16  of the user terminal  4 , and contains the information for identifying the product type of the user terminal  4 , such as the product type name specific to the user terminal  4 .  
         [0059]    Although the terminal information TI is preferably stored in advance in ROM  12  or the external storage unit  16  of the user terminal  4  as described above, a user may enter it manually.  
         [0060]    The music data request information RI is entered by using the music program information input window in the music data purchase home page displayed at Step SA 2 .  
         [0061]    At Step SA 4  the user terminal receives music data related information transmitted from the management server  2  at Step SB 9  to be described later. In accordance with the received music data related information, a list of purchasable qualities (hereinafter called a quality list) of the music data requested at Step SA 3  is displayed on the display  20 . Thereafter, the flow advances to Step SA 5 . The displayed quality list is, for example, a list such as shown in FIG. 4B or  4 C to be described later.  
         [0062]    At Step SA 5  the user is prompted to determine music data (commodity) to be purchased by referring to the quality list displayed at Step SA 4 . As the user selects the commodity and input the commodity information, the commodity information is transmitted to the management server  2  to thereafter advance to next Step SA 6 .  
         [0063]    At Step SA 6  a charging information input window such as shown in FIG. 4D to be described later is displayed on the display  20  to prompt the user to enter necessary purchase information. As the charging information is entered, this information is transmitted to the management server  2  to thereafter advance to next Step SA 7 .  
         [0064]    The necessary purchase information is the information containing at least charging information. In this embodiment, although the commodity is downloaded immediately thereafter, a storage medium storing the commodity may be mailed. In this case, the user is prompted to enter the charging information as well as the information on the commodity mailing method and the information on delivery such as a mailing date. A user may select one of the downloading and mailing or both may be selected.  
         [0065]    If charging is performed by using a credit card, the charging information contains a credit card number, an expiration date, an owner name and the like. If charging is performed by bank transfer or post office transfer, the information contains an address to which a transfer sheet is mailed or an email address to which a transfer sheet is transmitted. If charging is performed by e-cash, the charging information contains e-cash user information.  
         [0066]    At Step SA 7  the purchased music data is downloaded from the management server  2 . After the download, the flow advances to next Step SA 8 .  
         [0067]    At Step SA 8 , the process on the user terminal side is terminated.  
         [0068]    Next, the process on the management server side to be executed by CPU  14  of the management server  2  shown in the right side of FIG. 3 will be described.  
         [0069]    At Step SB 1  the process on the management server side starts. Thereafter, the process advances to next Step SB 2 .  
         [0070]    At Step SB 2  in response to a connection request from the user terminal, the music data purchase home page display file to be received at the user terminal  4  at Step SA 2  of the process on the user terminal side is transmitted to the Internet (communication network)  3  to thereafter advance to Step SB 3 .  
         [0071]    At Step SB 3  the management server receives the music data request information RI and terminal information TI transmitted from the user terminal  4  at Step SA 3  of the process on the user terminal side, and it is checked from the music data request information RI whether the original music data MO corresponding to the music data requested by the user is stored in the external storage unit  16  (FIG. 2). Thereafter, the flow advances to next Step SB 4 .  
         [0072]    At Step SB 4  if the check result at Step SB 3  indicates that the original music data MO requested by the user is stored in the external storage unit  16  (FIG. 2), then the flow advances to Step SB 7  indicated by a YES arrow. If the original music data MO requested by the user is not stored in the external storage unit  16  (FIG. 2), the flow branches to next Step SB 5  indicated by a NO arrow.  
         [0073]    At Step SB 5  the user terminal  4  is notified via the Internet (communication network)  3  of the effect that the music data requested by the user does not exist. Thereafter, the flow advances to next Step SB 6 .  
         [0074]    At Step SB 6  the process on the management server side is reset to return to Step SB 1  and resume the management server process.  
         [0075]    At Step SB 7  by referring to a correspondence table shown in FIG. 6B and the terminal information TI received at Step SB 3 , the management server determines the file format and quality of music data MD reproducible at the user terminal  4  which requested for the music data. Thereafter, the flow advances to next Step SB 8 .  
         [0076]    As shown in FIG. 6B, the correspondence table includes two types of tables for mobile phones and electronic musical instruments (tables are prepared for each reproducible apparatus and each file format). The correspondence table matching the user terminal is selected by referring to the terminal information TI. For example, if the user terminal is a mobile phone (as confirmed by the terminal information TI), the correspondence table matching the mobile phone is used. The correspondence table for the mobile phone stores reproducible qualities for each of portable terminal product types including “mobile phone AA01”, “mobile phone AB01”, . . . , “mobile phone ZZ99”. In FIG. 6B, a symbol “circle” indicates that music data of that quality can be reproduced, and a symbol “cross” indicates that the music data of that quality cannot be reproduced.  
         [0077]    For example, the “mobile phone AB01” cannot reproduce music data of the high quality, but it can reproduce music data of the middle and low qualities. In accordance with such information, a list DL shown in FIG. 4C is displayed.  
         [0078]    Conversion of the file format is judged from whether the user terminal apparatus (product type) represented by the terminal information TI belongs to (is recorded in) in the table for the mobile phone or the table for the electronic musical instrument. For example, if the user terminal apparatus is recorded in the mobile phone table, the file format is converted into the file format reproducible at the mobile phone.  
         [0079]    In this embodiment, the correspondence table is prepared for each reproducible file format. It is not necessarily required to prepare the correspondence table for each file format. However, in this case, it is necessary to record a reproducible file format for each product type.  
         [0080]    At Step SB 8  a price for each quality, determined at Step SB 7 , of music data reproducible at the user terminal  4  which requested for the music data is determined. Thereafter, the flow advances to next Step SB 9 . In determining the price for each quality, a table storing the price for each quality may be used, or a base price may be set to calculate from the base price the price for each quality by using a predetermined calculation method. In this embodiment, the price for each quality is recorded in a conversion table shown in FIG. 6C to be described later.  
         [0081]    At Step SB 9  the music data related information is transmitted to the user terminal  4  via the Internet  3  to prompt the user to purchase music data. The music data related information contains the quality of music data purchasable by the user determined at Step SB 7  and the price for each quality of the music data set at Step SB 8 . The transmitted music data related information is displayed as the quality list window shown in FIG. 4B or  4 C to be described later. Thereafter, the flow advances to next Step SB 10 .  
         [0082]    At Step SB 10  in response to an input (at Step SA 5 ) of commodity purchase information from the user terminal  4 , a file for displaying at the user terminal  4  a charging information input window such as shown in FIG. 4D to be described later is transmitted to prompt the user to enter the charging information. Thereafter, the flow advances to Step SB 11 .  
         [0083]    At Step SB 11  the management server receives the charging information transmitted from the user terminal  4  at Step SA 6  of the user terminal side process, and executes a charging process in accordance with the received charging information. Thereafter, the flow advances to next Step SB 12 .  
         [0084]    At Step SB 12  in accordance with the information on the commodity determined at Step SA 5  of the user terminal side process and received at Step SB 10  from the user terminal  4 , the music data of the quality determined at Step SA 5  of the user terminal side process is created from the original music data MO stored in the external storage unit  16  (FIG. 2), by referring to a conversion table shown in FIG. 6C. Thereafter, the flow advances to Step SB 13 .  
         [0085]    As shown in FIG. 6C, the conversion table includes two types of tables for mobile phones and for electronic musical instruments. Similar to the correspondence table, the table matching the user terminal is used. For example, the conversion table for the mobile phone records information on the quality of music data and a price for each quality of the high, middle and low qualities. The quality information includes the number of reproduction parts, presence/absence of pitch-bend data, presence/absence of tone color data, and presence/absence of score data. In FIG. 6C, a symbol “circle” indicates that the corresponding data is not removed, and a symbol “cross” indicates that the corresponding data is removed.  
         [0086]    For example, if the original music data is converted into the music data of the middle quality for a mobile phone, the mobile phone conversion table shown in FIG. 6C is used, and the number of reproduction parts is reduced to two channels, the pitch-bend data in the original music data is removed, and the store data is removed. The tone color data is the same as that in the original music data. The price is  120  Yen.  
         [0087]    The conversion table may be a table not only for the mobile phone and electronic musical instrument, but also for other apparatuses capable of reproducing music data. The price for the music data may be stored in the correspondence table shown in FIG. 6B or it may be stored in another table.  
         [0088]    At Step SB 13  by referring to the correspondence table shown in FIG. 6B, the file format of the created music data is converted into the file format reproducible at the user terminal  4 . Thereafter, the flow advances to next Step SB 14 .  
         [0089]    At Step SB 14  the music data MD purchased by the user and having the desired quality is transmitted to the user terminal  4  via the Internet  3 . The quality of the music data MD was changed at Step SB 12 , and the file format thereof was changed at Step SB 13  to the file format reproducible at the user terminal  4 . After the music data MD is transmitted, the flow advances to next Step SB 15 .  
         [0090]    At Step SB 15  the management server process is reset to return to Step SB 1 .  
         [0091]    [0091]FIGS. 4A to  4 D show examples of various display windows used for purchasing music data.  
         [0092]    [0092]FIG. 4A shows an example of the music program information input window displayed in the music data purchase home page on the display  20  of the user terminal  4 . The home page was transmitted from the management server  2  to the user terminal  4  at Step SB 2  shown in FIG. 3. The music program information input window is not necessarily required to be displayed in the music data purchase home page, but it may be displayed in another window.  
         [0093]    As shown in FIG. 4A, in the music program information input window, a message MG 1  such as “designate music program” is displayed to prompt the user to enter the music data request information RI, and a music program name input field  26   a  for inputting a music program name and a singer name input field  26   b  for inputting a singer name are disposed.  
         [0094]    The music program information input window is further provided with an “OK” switch SW 1  for enabling the input data and a “CANCEL” switch SW 2  for disabling the input data. These switches SW 1  and SW 2  are operated with a cursor  38 . If the product type name or the like is to be entered from a user, a product type name input field or the like is provided.  
         [0095]    A user enters a music program name in the music program name input field  26   a  and if possible the singer name in the singer name input field  26   b , moves the cursor  38  to the “OK” switch SW 1 , and clicks the cursor  38  with the operation unit such as a mouse. In this manner, the music data request information RI and terminal information TI are transmitted to the management server  2 .  
         [0096]    [0096]FIG. 4B shows an example of the quality list displayed in the music data purchase home page at Steps SA 4  and SA 5 . The quality list was transmitted at Step SB 9  shown in FIG. 3 from the management server  2  to the user terminal  4 . In the example shown in FIG. 4B, there are three types of purchasable qualities including the high, middle and low qualities of the music data requested at Step SA 3 . In this embodiment, although the quality list is displayed in the music data purchase home page instead of the music program information input window, it may be displayed in another window.  
         [0097]    As shown in FIG. 4B, with the quality list, a message MG 2  such as “designate commodity” is displayed to prompt the user to select a commodity, the music program name and user terminal name are displayed for user confirmation, and a commodity list DL of commodities usable at the user terminal is displayed.  
         [0098]    Radio buttons SW 3   a  to SW 3   c  are also displayed on the left side of the purchasable qualities including the high, middle and low qualities. The quality list is further provided with an “OK” switch SW 1  for enabling the input data and a “CANCEL” switch SW 2  for disabling the input data. These switches SWI and SW 2  and radio buttons SW 3   a  to SW 3   c  are operated with a cursor  38 .  
         [0099]    As a user clicks one of the radio buttons SW 3   a  to SW 3   c  and the “OK” switch SW 1  with the operation unit such as a mouse, the commodity is determined.  
         [0100]    The display example shown in FIG. 4B is used if the user terminal is of a high performance. In this case, the information of all the qualities from the high quality to low quality is displayed to allow the user to purchase music data of any one of the high to low qualities. If the user terminal is of a middle performance, the terminal can reproduce music data of only the middle and low qualities so that as shown in FIG. 4C, a list DL without the information for the high quality is displayed. The other displayed items are common to those shown in FIG. 4B. If the user terminal can reproduce music data of only one quality, a list DL with the information only for that quality is displayed. Also in this case, the other displayed items are common to those shown in FIG. 4B.  
         [0101]    [0101]FIG. 4D shows an example of the charging information input window displayed in the music data purchase home page at Steps SA 6 . The charging information input window was transmitted at Step SB 10  shown in FIG. 3 from the management server  2  to the user terminal  4 . The charging information input window is not necessarily required to be displayed in the music data purchase home page, but it may be displayed in another window.  
         [0102]    As shown in FIG. 4D, in the charging information input window, a message MG 3  such as “enter charging information” is displayed to prompt the user to enter charging information, and a charging information input field  26   c  is displayed for entering charging information. The music program name, quality and price are also displayed for user confirmation. The charging information input window is further provided with an “OK” switch SW 1  for enabling the input data and a “CANCEL” switch SW 2  for disabling the input data. These switches SW 1  and SW 2  are operated with a cursor  38 .  
         [0103]    As a user enters necessary charging information in the charging information input field  26   c  and clicks the “OK: switch SW 1  with the operation unit such as a mouse, the charging information is transmitted to the managing server  2 .  
         [0104]    [0104]FIG. 7 is a block diagram showing the main functions of the music data distribution system  1  having the management server  2 , network  3  and user terminal  4 .  
         [0105]    The management server  2  has at least: a music data storage unit  32  for storing the original music data MO; a music data request reception unit  33  for receiving music data request information from the user terminal  4 ; a charging unit  34  for charging a user; a transmission unit  35  for transmitting the music data MD to the user terminal  4  via the network  3 ; and a music data conversion unit  36  for converting the original music data MO into the music data MD in accordance with the music data request information of the user or the product type of the user terminal  4 .  
         [0106]    The user terminal  4  has at least: an input unit  26  for inputting user request and designation, various information necessary for downloading the music data MD, and the like; a terminal information storage unit  27  for storing terminal information to used by the management server  2  to identify the product type or the like of the user terminal  4 ; a music data request unit  28  for transmitting the music data request information RI and terminal information TI; a purchase setting unit  29  for transmitting and receiving information necessary for the charging process; a reception unit  30  for receiving the music data MD from the management server  2  via the network  3 ; and a music data storage unit  31  for storing the music data MD received at the reception unit  30 .  
         [0107]    A user inputs the music data request information RI from the input unit  26  of the user terminal  4 . The music data request information input from the input unit  26  is sent to the music data request unit  28 . The music data request unit  28  reads the terminal information TI specific to the terminal stored beforehand in the terminal information storage unit  27 , and transmits it together with the input music data request information RI to the management server  2  via the network  3 .  
         [0108]    On the management server  2  side, the music data request reception unit  33  receives the transmitted music data request information RI and terminal information TI. By referring to the music data request information RI, the music data request reception unit  33  checks whether the original music data MO corresponding to the music data request information RI is stored in the music data storage unit  32 . If the original music data MO corresponding to the music data request information RI is not stored, this effect is notified to the user terminal  4 .  
         [0109]    If the original music data MO corresponding to the music data request information RI is stored, the music data request reception unit  33  determines the quality reproducible at the user terminal  4  by referring to the terminal information TI and the correspondence table shown in FIG. 6B, and determines the music data reproducible at the user terminal  4  and its price by referring to the price for each quality recorded in the conversion table shown in FIG. 6C or the like. The determined quality and price are sent to the charging unit.  
         [0110]    In accordance with an instruction and information supplied from the music data request reception unit  33 , the charging unit  34  transmits the list DL (FIG. 4C) of qualities and prices of the music data to the user terminal  4  and prompts the user to purchase music data.  
         [0111]    The purchase setting unit of the user terminal  4  receives the list DL of qualities and prices of the music data and displays it on the display  20  (FIG. 2). By referring to the list DL, the user selects the commodity by operating upon the input unit  26 . The input unit  26  sends the information of the commodity selected by the user to the purchase setting unit  29 . The purchase setting unit  29  transmits the information on the quality of the purchased music data to the charging unit  34  via the network  3 .  
         [0112]    Upon reception of the information on the quality of the purchased music data from the purchase setting unit  29 , the charging unit  34  prompts the purchase setting unit  29  to transmit the charging information, and instructs the music data conversion unit  36  to prepare the music data MD. At this time, information on the original music data MO to be converted, the file format to be converted of the music data MD, the quality and the like are also transmitted to the music data conversion unit  36 .  
         [0113]    In response to the instruction from the charging unit  34 , the music data conversion unit  36  reads the original music data MO from the music data storage unit  32 . The read original music data MO is converted by using the conversion table shown in FIG. 6C to make the music data MD have the quality requested by the user, and by using the correspondence table shown in FIG. 6B to make the music data have the file format reproducible at the user terminal  4  (the file format matching the user terminal environment). The music data MD converted by the music data conversion unit  36  is sent to the transmission unit  35 .  
         [0114]    The music data conversion unit  33  may be replaced by a music data selection unit. The music data selection unit selectively reads the requested music data reproducible at the user terminal from the music data storage unit  32 . In this case, the music data storage unit  32  stores music data being reproducible at a plurality type of user terminals and corresponding to a plurality type of qualities, for each of a plurality of music programs.  
         [0115]    The purchase setting unit  29  prompted to transmit the charging information by the charging unit  34  prompts the user to enter the charging information. The user enters the charging information. The input charging information is transmitted to the charging unit  34  via the network  3 .  
         [0116]    In accordance with the received charging information, the charging unit  34  performs a process necessary for charging, and instructs the transmission unit  35  to transmit the music data MD to the user terminal  4 .  
         [0117]    Upon reception of the instruction from the charging unit  34 , the transmission unit  35  transmits the music data MD to the user terminal  4  via the network  3 .  
         [0118]    The reception unit  30  of the user terminal  4  receives the music data MD and sequentially stores it in the music data storage unit  31 .  
         [0119]    As described above, according to the embodiment of the invention, it is possible to distribute music data recorded by one file format by converting the file format into file formats (e.g., for electronic musical instruments and mobile phones) reproducible at various apparatuses.  
         [0120]    Further, according to the embodiment of the invention, irrespective of the product type of the apparatus owned by a user, such as an electronic musical instrument and a mobile phone, proper music data can be purchased with ease.  
         [0121]    Still further, according to the embodiment of the invention, music data converted into various qualities (music data having various data amounts) can be distributed.  
         [0122]    Furthermore, according to the embodiment of the invention, a user can purchase music data of a desired quality at a reasonable price.  
         [0123]    In the embodiment, a user selects one of qualities prepared beforehand for music data. Instead, the music data distribution system may be structured so that a user can select freely the detailed contents of each quality. For example, the detailed contents may be selected to the degree that the user terminal can deal with them (can reproduce the music data with the altered quality contents). In this case, charging is performed in accordance with the altered quality contents.  
         [0124]    In this manner, a user can purchase music data having a finer quality desired by the user.  
         [0125]    In this embodiment, although the quality of music data is changed depending upon presence/absence of particular musical performance data, the quality of music data may be changed by altering the contents of particular musical performance data.  
         [0126]    [0126]FIG. 8 shows an example of the conversion table for an electronic musical instrument for converting the contents of particular musical performance data. As shown in FIG. 8, the table records the detailed contents of particular musical performance data for each quality of music data to be converted.  
         [0127]    For example, when the original music data MO is converted into the music data MD of the middle quality, although a resolution of sound producing timings is restricted, the original music data MO is converted into the music data having rhythmical sense. For the low quality, the original music data is converted into the music data without rhythmical sense through quantization.  
         [0128]    As to the length of a music program, when the original music data MO is converted into the music data MD of the middle quality, an introduction, an interlude, and an ending are shortened, and for the low quality, the original data MO is shortened only to one chorus or to a motif part (main theme of the music).  
         [0129]    In this manner, as the quality is lowered, the amount of musical performance data is reduced. Namely, the music data of the low quality has the musical performance data less than that of the music data of the high quality, so that a time taken to download the music data can be shortened.  
         [0130]    In the above embodiment, although three qualities and three prices are set for the music data, the number of qualities and prices may be set as desired. For example, four or more qualities may be set and corresponding prices are set finely.  
         [0131]    In the embodiment, the original music data MO of the high quality is prepared and the musical performance data amount is reduced to change the quality. Instead, music data of a low quality or middle quality may be used as the original music data MO and some musical performance data is added to improve the quality and create musical data of a higher quality. In this manner, the capacity of the external storage unit of the management server  2  can be reduced.  
         [0132]    An audition function of allowing a user to audition a music program of each quality before purchasing it may be provided. Since the user can check the contents and quality of music data desired to purchase, the proper quality can be selected more easily.  
         [0133]    In this case, Steps SB 12  and SB 13  are performed between Steps SB 9  and SB 10  to convert the quality and file format of requested music data and allow the user to audition the music program. It is not necessary to convert all of the music data for audition, but only a portion thereof may be converted.  
         [0134]    Also in the embodiment, although a computer or portable data terminal is used as the user terminal (information communication terminal), other apparatus may also be used so long as they have an automatic performance function and a display. For example, an electronic musical instrument with a keyboard, a mobile phone with a tone generator, a karaoke apparatus, a game apparatus, an automatic performance piano or the like may also be used. The type of an electronic musical instrument is not limited only to a keyed musical instrument, but other types may also be used such as a stringed instrument, a wind instrument and a percussion instrument. The electronic musical apparatus is not limited only to an electronic musical instrument of the type that the components thereof such as a tone generator and an automatic performance apparatus are all built in one integrated body, but these components may be discrete and interconnected by communication devices such as MIDI and various networks.  
         [0135]    The embodiment may be realized by a commercially available general computer installed with the computer program and the like realizing the functions of the embodiment.  
         [0136]    In such a case, the computer program and the like realizing the embodiment functions may be stored in a computer readable storage medium such as a CD-ROM and a floppy disc and supplied to users.  
         [0137]    If a general purpose computer or personal computer is connected to a communication network such as a LAN, the Internet and a telephone line, the computer program and various data may be supplied to the general purpose computer or personal computer via the communication network.  
         [0138]    The present invention has been described in connection with the preferred embodiments. The invention is not limited only to the above embodiments. It is apparent that various modifications, improvements, combinations, and the like can be made by those skilled in the art.